Biodiversity of Vascular Plants in Bulgaria

Dimitar Peev, Stefan Kozuharov , Mincho Anchev, Ana Petrova, Daniela Ivanova, and Sonia Tzoneva

Introduction

Although Bulgaria's territory is small, its flora is characterized by considerable species richness. The number of higher plant species in Bulgaria - about 3550-3750 - is greater than that in many larger countries. The same can be said of other groups of plants - algae (about 4000), mosses (670), lichens (600), and ferns (52). (These figures are not final, since field investigations continue.)

The structure of Bulgarian plant diversity can be illustrated by looking at one of the best studied groups - the seed plants (3476 species). Native gymnosperms - all of which are trees and shrubs, including conifers in the families Pinaceae and Cupressaceae - amount to fifteen species. If the angiospermous trees and shrubs are added, the Bulgarian phanerogamous flora adds up to 359 species. Seven hundred to 1000 years ago, most of Bulgaria up to an altitude of 2200-2300 meters above sea level (a.s.l.) was covered with trees and shrubs. At that time the forests were probably richer in species than at present (forests currently cover only about 31% of the territory of Bulgaria). Today much of the Bulgarian forest cover consists of wood cultures poor in species diversity. The herbaceous angiosperm flora is the richest in species (3241), the majority of which are perennials. This abundance of perennials reflects the moderate continental climate of Bulgaria, which is favorable for their occurrence and establishment.

History of Botanical Investigations

Over the last thirty years, taxonomic research in Bulgaria has developed intensively due both to internal and external factors. The relative degree of economic and social progress in the country has had a favorable effect on natural science research in general. Major taxonomic and floristic studies in neighboring countries and the rest of Europe have also favored this development. The completion of the remarkable Flora of Turkey, the Flora SR Srbje, the elaboration of a project for "Analytica flora Jugoslaviae," and the recent "Flora of Greece" project all reflect the intensification of taxonomic and floristic studies in this region. These activities provide an ever-increasing and improving base for the continental project "Flora Europaea."

Four main periods can be identified in the development of floristic and taxonomic research on the Bulgarian flora:

1. The period prior to the publication of Velenovsky's Flora Bulgarica (1891, 1898), during which studies were performed almost exclusively by foreign botanists.

2. The period up to the publication of Stojanov and Stefanov's Flora na Bulgaria (1924-1925), characterized by very intensive floristic studies by both Bulgarian and foreign botanists.

3. The period up to the publication of the first volume of Flora RP Bulgaricae (Jordanov, 1963) [Flora of the People's Republic of Bulgaria - ed.], characterized by the first monographic and taxonomic revisions of genera or sections, including Colchicum, Centaurea, Dianthus, Cerastium, and Anthemis.

4. The last thirty years, which marks the successful realization of the nine volumes of Flora RP Bulgaricae, the major project of taxonomic botany in the country, and the compilation of the first local flora of Vitosha Mountain, the Pirin Mountains, and Dobrudzha.

This last period has seen great advances in a number of key areas of research. As taxonomic investigations have progressed, modern methods have been introduced - karyological, cytotaxonomical, embryological, anatomical, chemical, palynological, and biometrical (Kuzmanov, 1974). Taxonomic studies and species concepts have been influenced by the ideas and methods of biosystematics and cytotaxonomy (Kozuharov and Kuzmanov, 1968). The role of genetic, cytological, embryological, chemical, and experimental data in delimiting and describing taxa is better appreciated. Nomenclatural problems have steadily received more attention, especially in connection with the Flora RP Bulgaricae project. This project has also stressed the importance of international collaboration; herbarium material and literature have been exchanged on an scale previously unknown in Bulgaria. Finally, taxonomic research in this period has also been characterized by the use of the type-concept and typification of taxa (Kuzmanov, 1971).

The increased number of botanists devoted to floristics and taxonomy has not only contributed to the intensification of research in the recent past, but has also made possible recent discussions of a new project for the next decade: a detailed local flora of the Rhodope Mountains. This is to be undertaken by a group of botanists in Plovdiv.

Gaps in Knowledge

Current gaps in our knowledge of the higher plants of Bulgaria can be summarized as follows:

1. The treatment of taxa by past and present authors has varied. A revision of nearly 500 taxa is absolutely necessary. This process has begun, but is not yet finished.

2. Detailed chorological information for the distribution of certain species or species groups is lacking for the Sakhar region, the Tundzha hilly region, the eastern and western Rhodopes, the western border mountains, and other areas. These areas are poorly investigated because of their large area and difficult topography.

3. We lack biodiversity information for the group of families from Dipsacaceae and Asteraceae (about 400 species). This information will appear in the last three volumes of the Flora RP Bulgaricae.

4. Investigations on karyology and chromosome numbers are proceeding. At present, about 1500 populations from 1200 species are being studied.

5. Only about 500 populations have been investigated statistically. Because of the high number of endemic and relict species, such population-level investigations are needed to ascertain the nature and direction (if any) of variation.

6. In the past, the mapping of the distribution of Bulgaria's higher plants was limited for political reasons. The restrictions of the secret service made it impossible to use 1:20000 maps for field work.

7. Pollen analysis, stomatal analysis, and microstructural analysis of the seed testa are progressing more slowly than biodiversity studies.

8. Fundamental embryological investigations to help explain the process of speciation for many Bulgarian endemics are still insufficient.

9. The effects of genetic drift in many of the rare and threatened species are not clear.

10. From a botanical perspective, the protected areas have not been equally or adequately inventoried at the species level.

These knowledge gaps can be placed into two main groups: those involving problems that require new research (chorology, genecology, embryology, statistics, karyology, chemotaxonomy, etc.); and those involving problems that require confirmation and checking (distribution, density of populations, morphology, more accurate descriptions based on the herbarium materials, etc.).

Biodiversity of Higher Plants in Bulgaria

The higher plants of Bulgaria have been classified in 130 families and 872 genera, with 3550-3750 species, 847 subspecies, and 2000 varieties. Systematically the higher plants in the Bulgarian flora are grouped as follows: Pteridophyta - 58 species; Gymnospermae - 16 spp.; Angiospermae - 3460 spp.; Monocotyledonae - 568 spp.; and Dicotyledonae - 2613 spp.

The order Pteridophyta in Bulgaria is represented by 28 genera with 58 species, organized in three classes: Lycopodiopsida, Equisetopsida, and Filicopsida. Only Salvinia natans (L) All. is annual; the others are perennial. The class Lycopodiopsida includes 8 species from 6 genera in three families (Isoetaceae, Lycopodiaceae, and Saliginellaceae). The class Equisetopsida is represented by 7 species from the genus Equisetum in the family Equisetaceae. The Bulgarian flora of the class Filicopsida are grouped into 15 families. Seven of these families are represented by single species within the genera Adiantaceae, Blechnaceae, Cryptogrammaceae, Hypolepidaceae, Marsileaceae, Osmundaceae, and Salviniceae. The best represented families are Aspidiaceae (10 species from 3 genera) and Aspleniaceae (11 species from 3 genera). The other 6 families - Athyriaceae, Azollaceae, Ophioglossaceae, Polypodiaceae, Sinopteridaceae, and Thelypteridaceae - are represented by one or two genera with 2-4 species. The most widely spread pteridophyte species are Athyrium filix-femina (L.) Roth, Dryopteris filixmas (L.) Schott, Polystichum lonchitis (L.) Roth, and Pteridium aquilinum (L.) Kuhn.

Among the seed-bearing higher plants, the most represented families are: Fabaceae - 278 spp.; Poaceae - 237 spp.; Asteraceae - 470 spp., Rosaceae - 207 spp. Other well represented families include: Caryophyllaceae - 187 spp.; Brassicaceae - 169 spp; Apiaceae - 147 spp.; and Lamiaceae - 130 spp. Though not so rich in species, several plant families, including Pinaceae, Fagaceae, and Aceraceae, are of great significance for the Bulgarian flora. Many of the species in these families are dominants within forest ecosystems and form the basis for delineation of the main vegetation zones in Bulgaria.

The families and genera richest in dominant species are: Fagaceae (Quercus - 26 spp.); Poaceae (Festuca - 36 spp; Bromus - 26 spp.; Poa - 14 spp.); Fabaceae (Trifolium - 59 spp.; Vicia - 36 spp.; Lathyrus - 28 spp.; Medicago - 14 spp); Asteraceae (Centaurea - 35 spp.; Anthemis - 14 spp.; Senecio - 18 spp.); Rosaceae (Rosa - 44 spp.; Potentilla - 34 spp.; Alchemilla - 35 spp.); Brassicaceae (Cardamine - 17 spp.; Allyssum - 13 spp.); Caryophyllaceae (Dianthus - 22 spp.; Minuartia - 19 spp.; Cerastuim - 18 spp.); Lamiaceae (Thymus - 25 spp.; Stachys - 20 spp.). There are 30 genera with more than 20 species, 464 genera with between 10 and 20 species, and 100 genera with more than 10 species.

lowlands, plains, the belts of the xerotherm oak forests, and the mesophyte and xeromesophyte oak and hornbeam forests up to 700-900 m above sea level (a.s.l.). The flora of the Stara Planina Mountains is the richest in species diversity. Then follow the Rhodopes, the Pirins, the Rilas, the calcareous mountains of Western Bulgaria, Osogovo Mountain, Strandzha Mountain, and the lowlands - the Strouma River valley, the Thracian Plain, the Tundzha hilly region, the Black Sea coast together with Dobrudzha, and the Danubian plain.

In general, the number of species present in these sub-regions reflects not only the size of the massif (in the case of the mountain flora), but also their altitudinal and ecosystemic variation. Altitudinally, 2246 species occur in the zone be-tween sea level and 500 m a.s.l.; 2137 species from 500 to 1000 m a.s.l.; 780 species from 1000 to 2500 m a.s.l.; and 780 species at altitudes over 1800 m a.s.l. Only 144 constant species occur above 2500 m a.s.l. The flora that occurs on calcareous rock substrates is richer in species than that which occurs on a silicate base.

Bulgarian plants can be grouped into perennials (2264 spp), biannuals (353 spp.), and annuals (515 spp.). The large number of perennial species, combined with the high degree of variation in altitude, ecological niches, and phytoclimatic influences, provides favorable conditions for active evolutionary processes. The conditions of ecological isolation provide the basis for speciation processes in Bulgaria, with structural heterozygosity as the main evolutionary mechanism. Heterozygosity leads to gradual speciation through chromosomal changes and diploidy and aneuploidy. The incidence of polyploidy is much lower, about 30%.

A Review of the Taxonomic Literature

Over the last century, some 10,000 articles on the Bulgarian flora have been published. About 70% are directly concerned with the chorology of higher plants - their distribution in the country as a whole, their distribution in different regions, the occurrence of species new to science, and the occurrence of new species for the country or for a particular region. Ten percent of these articles deal with questions of the evolution, variation, and taxonomy of particular groups of higher plants. The most completely studied plant families are Poaceae, Linaceae, Caryophyllaceae, Scrophulariaceae, Primulaceae, Rubiaceae, and Lamiaceae. The remaining 20% of these scientific works concern anatomy, morphology, karyology, stomatal analysis, and other aspects of the biology of higher plants.

A particularly important source of scientific information is Flora RP Bulgaricae, which summarizes all that has been learned about the Bulgarian flora at the species and subspecies level. At this point, nine volumes have been edited and a tenth is in press. The plant families Campanulaceae and Asteraceae will be covered in the next three volumes. These volumes provide information on nomenclature, morphological peculiarities, intraspecific variation, distribution in the country, and geographical distribution. This flora is the only one which differs essentially from the synopses and guides to higher plants that currently exist.

The 213 articles listed at the end of this paper include the most important reports on Bulgarian taxonomical investigations, and illustrate the extent of, and advance degree of knowledge about, biological diversity in the Bulgarian flora, even at the population level.

Endemics: Speciation, Distribution, and Protection

At present, about 170 species and 100 subspecies of angiospermous higher plants have been identified as Bulgarian endemics. Among the 3500 species and 840 sub-species of higher plants described so far, Bulgarian endemics constitute about 4.86 per cent. This is a relatively high ratio compared to the percentage of endemics in other European countries with larger territories. The proportion of endemic subspecies is even higher - 8 per cent. The percentage of endemic species would increase significantly if it included Balkan endemic species that occur in Bulgaria. It is quite possible that some of them originated in Bulgaria (especially in the Rhodopes, the Pirin Mountains, and Slavyanka Mountain) and later on spread to other parts of the Balkan Peninsula. This may have happened during various epochs of the Quaternary.

Ongoing studies of species (and other taxa) that are currently considered Bulgarian endemics may lead to the identification of new habitats in other parts of the Balkan Peninsula. Such is the case, for example, for Geum bulgaricum Panc. and Astragalus physocalix Fisch. The first is found in the Rila Mountains, and the second other in the Thracian plain. Recently, however, both have been found in different parts of the former Yugoslavia.

In general, the occurrence of endemic plants in Bulgaria reflects the special habitats and genetic peculiarities of its flora. The relatively high degree of endemism testifies to the richness of Bulgaria's characteristic ecological niches and its varied phytogenetic and phytoclimatic history.

Families and Species

The family Asteraceae contains the greatest number of Bulgarian endemics - 38 species and 12 subspecies. It is followed by: Caryophyllaceae (18 spp., 10 subspp.); Scrphulariaceae (11 spp., 14 subspp.); Rosaceae (15 spp., 3 subspp.); and Poaceae (12 spp., 4 subspp.). Among the genera, the greatest number of Bulgarian endemics is to be found in the genus Centaurea from the family Asteraceae - 8 species and 16 subspecies. It is followed by: the genus Verbascum from the family Scrophulariaceae (8 spp., 4 subspp.); the genus Anthemis from the family Asteraceae (10 spp.); the genus Silene from the family Caryophillaceae (6 spp., 1 subsp.); and the genus Alchemilla from the family Rosaceae (6 spp.).

Distribution

The distribution of endemic Bulgarian higher plants is quite uneven, and is related primarily to the presence of mountains. Of all the mountain groups, the Stara Planina Mountains are the richest in endemics. Over 90 Bulgarian endemic species and subspecies occur there, and more than 20 of them are local. These include: Primula frondosa Janka, Betonica bulgarica Deg. et Neic., Viola balcanica Delip., Festuca bosniaca (Acht.) Markgr. -Dannb., Leontopodium alpinum subsp. slavicum Urum., Alchemilla jumrukczalica Pawl., and Seseli degenii Urum.

The Rhodopes rank second in the number of endemics. Over 80 species and subspecies of Bulgarian higher plant endemics are found there. About 20% occur in that region only. Among them are: Arenaria rhodopaea Delip., Rosa rhodopaea Dim., Quercus thracica Stef. et Ned., Ranunculus stojanovii Delip., Gypsophila tekirae Stef., Lilium rhodopaeum Delip., and Scabiosa rhodopensis Stoj. et Stef.

Third in rank are the Pirin Mountains. Over 70 endemic species and subspecies have been recorded there, more than 30 of which are local or narrowly regional Pirin endemics. Some of the most typical are: Arenaria pirinica Stoj., Centaurea achtarovii Urum., Papaver degenii (Urum. et Jav.) Kusm., Brassica jordanoffii O.E. Schulz, Oxytropis urumovii Deg., Verbascum davidovii Murb., Festuca pirinica Horv. ex Markgr.-Dannb., Linum alpinum subsp. pirinicum Petrova, and Carex pratensis Acht.

Fourth in rank are the Rila Mountains, where about 50 species and subspecies of Bulgarian higher plant endemics can be found. Ten of these are confined to that mountain massif alone. Typical endemic species here are Quercus mestensis Bond. et Ganc., Rheum rhaponticum L., Anthemis orbelica Panc., and Primula deorum Vel.

The other mountains rank as follows: Vitosha (25 spp. and subspp.); Strandzha (19); Sredna Gora (12); Belasitsa (8); Osogovo (6).

Relatively few endemic species and subspecies are found in the lowlands and the low mountain foothills. In the lowlands they are preserved mainly in the lower hills with shrub and herbaceous vegetation, where they were undoubtedly widespread in the past. Here occur: Chamaecytisus kovacevii (Vel.) Rothm., Linum tauricum subsp. bulgaricum (Podp.) Petrova, Onosma thracica Vel., Medicago rhodopea Vel., Galium rhodopeum Vel., Festuca thracica (Acht.) Markgr.-Dannb., Limonium bulgaricum Ancev, Verbascum dieckianum Borb. et Deg., Crepis stojanovii T. Georg., Bromus moesiacus Vel., Astracantha aitosensis (Ivanisch.) Podl., and others. Some species in this group have quite small populations, as, for example, Quercus thracica Stef. et Ned., Eranthis bulgaricus Stef., Linum tauricum subsp. bulgaricum (Podp.) Petrova, Hedysarum grandiflorum subsp. bulgaricum Koz., Hypericum setiferum Stef., Anthemis argyrophylla (Hal. et Georg.) Vel., and Tulipa splendens Delip.

Balkan endemics comprise a sizable part in the composition of the Bulgarian higher flora. They number about 200 species and subspecies. Many were first identified and described in Bulgaria, and so carry the name or names of Bulgarian mountains and scientists. Examples include Dianthus drenovskyanus Rech. fil., Geum bulgaricum Panc., Rhamnus rhodopeus Vel., Alchemilla bulgarica Rothm., Oxitropis urumovii Jav., Viola perinensis W. Becker, Lathraea rhodopaea Dingl., Geum rhodopeum Vel., Haberlea rhodopensis Friv., Festuca riloensis (Hack. et Hay.) Markgr.-Dannb., and Fritillaria drenovskii Deg. et Stoj.

Many of the Balkan higher endemics occur mainly in Bulgaria. This is the case, for example, with Silene skorpilii Vel., Dianthus microlepis Boiss., Aquilegia aurea Janka, Astracantha thracica (Griseb.) Podl., Acer heldreichii Orph. ex Boiss., Alkanna stribrnyi Vel., Satureja pilosa Vel., Verbascum adrianopolitanum Podp., and Festuca valida (Uechtr.) Penzes. The group of Balkan endemics includes Abies borisiregis Matf. and Pinus peuce Griseb., the second of which is widespread in the Bulgarian mountains and an extremely valuable forest tree in terms both of economics and ecology.

A number of factors account for the high proportion of Bulgarian and Balkan endemics in the higher flora of our country. Of major importance are:

• Bulgaria's location at the crossroads of three phytocli-matic regions - the European deciduous forest, the Asian steppe, and the Mediterranean;
  
  
• the variety of climatic conditions due to the high mountain massifs, lowlands, plains, and the influence of the Black and Aegean Seas; these allow various vegetation elements - arctic, subarctic, middle-European, steppe, and mediterranean - to occur here;
  
  
• the wide range of ecological niches within the separate natural regions (bioclimatic zones, altitudinal belts, etc.) due to the complex topography and the highly variable rock substrates, soil types, and hydrological conditions; and
  
  
• the rich geological history of our lands.

Age and Classification of Endemics

Based on the degree of taxonomic specificity and the geographical isolation associated with it, Bulgarian endemics can be placed in the following categories:

1. Relict endemics

These are morphologically isolated species with no relations of the genus or section in the Balkan Peninsula. Such are the species that were formed during the Tertiary and endured the glacial epochs of the Quaternary in habitats that were relatively far from the centers of glaciation. Relict endemics form the smallest group in the Bulgarian flora. Because the territory that is now included within Bulgaria has been glaciated several times, surviving Tertiary relicts are not very numerous (as a rule they are morphologically primitive and have low chromosome numbers). Within this group fall most of the Balkan endemics, such as Aesculus hyppocastanum L., Viola delphinantha Boiss., and Centhranthus kellererii (Stoj., Stef. et T.Georg.) Stoj. et Stef.

2. Old endemics or palaeoendemics

These are morphologically or geographically isolated species that are, however, represented on the Balkan Peninsula or in neighboring territories by other, though not always closely related, single or several species. Such are: Pinus peuce Griseb., Pinus heldreichii Christ., Lathraea rhodopea Dingl., Ramonda serbica Panc., Aquilegia aurea Janka, Astracantha aitosensis (Ivanisch.) Podl., Astracantha thracica (Griseb.) Podl., Eranthis bulgaricus Stef., Gypsophila tekirae Stef., Acer heldreichii Orph. ex Boiss., Festucopsis sancta (Janka) Meld., Bromus moesiacus Vel., and Anthemis argyrophilla (Hall. et Georg.) Vel. Most endemics of this type occur in the lowlands and the lower mountain belt (up to 1000-1200 m), which indicates their thermophilic nature and therefore their affiliation with warmer climates.

3. Comparatively old species (semipalaeoendemics)

These are morphologically and geographically or ecologically well differentiated species belonging to genera or sections well represented in Bulgaria or the Balkan Peninsula, and that are very often isolated from other species by physical boundaries (e.g., seas). This group includes: Edrianthus serbicus Panc., Primula deorum Vel., Primula frondosa Janka; the species from the genus Saxifraga and its various sections - Saxifraga stribrnyi Vel., S. ferdinandi-coburgi Kell. et Sund.; Arenaria rhodopaea Delip., Alopecurus riloensis (Hack.) Pawl., and Viola perinensis W. Becker. Most of the endemics of this type occur in the medium and high mountain belt, mainly on calcareous ground, sometimes, however, coming down to the lower mountain belts.

4. Comparatively young (semi-recent) species

These are morphologically well differentiated species with close taxonomic relations in the Balkan Peninsula or in other neighboring countries. To this group belong species within the genera Lilium (L. rhodopaeum Delip., L. jankae Kern., and L. albanicum Griseb.); Tulipa (T. urumoffii Hay., T. thracica Dav., and T. rhodopaea (Vel.) Vel.); Verbascum (V. decorum Vel., V. dieckianum Borb. et Deg., V. juruk Stef., and V. minutiflorum Vel.); Galium (G. rhodopeum Vel.; Colchicum (C. davidovii Stef. and C. diampolis Delip. et Ceschm.); and the species Gentianella bulgarica (Vel.) Holub and Fritillaria drenovskii Deg. et Stoj.

5. Microspecies

These are species distinguished by fewer characters growing in one and the same or in neighboring areas (sympatric). Included in this category are mainly the apomictic complexes of a clonal nature, such as species from the genera Alchemilla (A. pirinica Pawl., A. achtarovii Pawl., A. jumrukczalica Pawl., A. pawlowskii Assenov, and A. asteroantha Rothm.); Rosa (R. pontica Dim., R. parilica Dim., R. bulgarica Dim., and other roses); and Hieracium (H. samokovense T. Georg., H. stefanoffii Zahn et Markgr., H. jankae Uechtr., H. pirinicolum T. Georg., and H. heuffelii Janka.

Speciation Centers

Centers of speciation are areas where the most active speciation processes take place. In the Bulgarian flora, local speciation centers developed in areas where contacts between various populations and species occurred as a result of encounters during migrations at different times and of varied duration.

Primary speciation centers are those that were not occupied by forest communities in the past. Secondary speciation centers are those that are situated in former forest areas, most often destroyed as a result of human activities. In Bulgaria, the first type is represented by the high mountain centers - above 2000 m altitude. The secondary centers are situated on the mountain slopes and in the foothills and lower hills. Speciation centers also differ in their basic rock composition - calcareous, serpentinite (basic or ultra basic), and silicate. Their boundaries are determined using available information about their floristic complexes (Velcev, ed., 1992).

The main difference between typical speciation centers and refugia is that the former includes, apart from old and young species, a relatively high degree of genetic variability in current populations. Refugia include primarily stabilized species that lack such variability. Consequently, from the viewpoint of their dwellers, they belong to the categories of old and comparatively old species. However, the genetic aspects of the Bulgarian speciation centers are insufficiently studied.

Distribution and Concentration of Endemic Taxa

According to the number of endemic taxa they contain, the Bulgarian floristic regions can be classified as follows:

1. Bulgarian endemics

The Rhodopes - 39 species; Stara Planina - 31; Pirin Mountains - 27; Thracian plain - 20; Black Sea coast - 17; Tundzha hilly region - 12; Rila Mountains - 11; Slavyanka Mountain - 11; Northeastern Bulgaria - 10; Strandzha mountain - 10; Balkan foothill region - 9; Znepole region - 6; Strouma River valley - 4; Danubian plain - 3; Western border mountains - 1; Vitosha region - 1; Mesta River valley - 1.

2. Balkan endemics

The Rhodopes - 56 species; Pirin Mountains - 40; Stara Planina - 36; Slavyanka Mountain - 31; Rila Mountains - 22; Znepole region - 17; Tundza hilly region - 14; Thracian plain - 13; Black Sea coast - 12; Strouma River valley - 12; Vitosha region - 12; Balkan foothill region - 10; Strandzha mountain - 7; Belasitsa - 6; Northeastern Bulgaria - 6; Sredna Gora Mountain - 5; Western border mountains - 5; Osogovo Mountain - 4; Danubian plain - 3; Mesta River valley - 2; Sofia region - 2.

Threats to the Natural Flora

As a result of developments in agriculture, stockbreeding, timber production, and other forms of land use, the natural ecosystems over vast areas of Bulgaria (about 2/3 of the total territory) have been drastically altered. Because of forest destruction in the lower mountain vegetational belt and hilly regions, the problem of soil erosion (especially on the southern slopes of the Stara Planina Mountains, the eastern Rhodopes, the southern and western slopes of the Pirin Mountains, and Ograzden) is widespread. In order to obtain new lands for agriculture, many natural wetlands and lakes have been drained.

Pastures that are overcrowded with cattle and sheep lose many species and suffer destruction of their grass cover. Many of the original species are replaced by harsh inefficient herbs or grasses such as Nardus stricta, which is a dominant species in many high mountain meadows. The late haymaking practiced normally in most districts of the country, combined with irregular irrigation, make the meadows rich in weeds and ruderals. Consequently, the hay is rough.

Air pollution is an indirect but important influence on the degradation of the vegetation. This is becoming more dangerous, to the point of causing definite alternations in microclimatic conditions.

These forces have led to the loss of diversity within the genepool, and of species such as Aldrovanda vesiculosa, Hottonia palustris, Salix rosmarinifolia, and Astragalus physocalyx. These and many others have been permanently lost, and illustrate not only the irreversibility of such losses, but the deep structural changes that subsequently occur within their ecosystems.

Over the last several decades, national goals called for the building of many factories, dams, houses, blocks of flats, power stations, and mines. And they were built. The road and the railway networks had to be enlarged as well. And they were. The rising demand for building materials caused an increase in forest exploitation, which in some regions had an immediate impact on the water resources.

Meanwhile, industry began to show the other side of the coin to nature. The increasing occurrence of smog has resulted in the degradation of many plant communities, e.g. in the southern slopes of the Stara Planina Mountains between the towns of Zlatitsa and Pirdop (where new copper works were situated), on Golo Bardo Mountain (site of the "Pernik" mines and metalurgic works), and in central Thrace (site of the "Maritsa-Iztoc" mines).

Unforeseen and unfavorable changes have arisen due to changes in the hydrology of some river systems as a result of the building of artificial lakes and dams.

In addition, one must not underestimate the effects of resort complexes and tourist movement (so strong nowadays) on the natural ecosystems, as well as the insufficiently regulated gathering of herbs.

And last but not least, the deep reorganization in the system of agriculture - the incorporation of the land in collective farms and the subsequent intensification of chemical fertilization and extensive use of pesticides - should also be mentioned as having had a definite impact on the natural and semi-natural plant communities.

Protection of the Natural Flora

The 1930s saw the rise of a real scientific movement for protection of Bulgaria's natural flora and vegetation. The first reserves aimed at conserving species considered rare and diminishing (mainly endemics and relicts) were created at that time. However, the rates of exploitation of the natural environment were far stronger and more advanced than the measures taken to protect the flora and vegetation of Bulgaria.

These results of general economic development might have been considered unavoidable. At the same time, however, efforts to balance these impacts with protective measures began. A number of serious measures for nature protection were realized. New reserves and national parks - Vitosha Mountain, Vihren Peak in the Pirin Mountains, Ostritsa Peak of Golo Bardo Mountain, Cervenata Stena in the central Rhodopes - were established. A long list of endemic relict species and species threatened with extinction was prepared in order to protect the taxa in greatest danger, as well as some natural complexes. The problems seemed to have been solved; in reality, however, they have not. In the 1985 Red Data Book of the People's Republic of Bulgaria, Volume 1: Plants, it is noted that during the last fifty years 31 species of higher plants have gone extinct. One hundred and fifty species are threatened with extinction. Five hundred and seventy-four species are noted to be of special scientific interest, while 330 species are protected by the Law of Protection of Nature.

Planning has now begun to address the plant conservation situation. Part of this effort is the Concept for the Protection of the Natural Flora and Vegetation elaborated by the Institute of Botany of the Bulgarian Academy of Sciences. The following basic ideas underlie the Concept:

1. The building of a system of reservations and national parks that includes all interesting and ecologically rich floristic and vegetational regions.

2. The protection of habitats with rare, endemic, and relict plants and phytocoenoses not included, for whatever reason, in the reservations, as botanical localities of special importance.

3. The protection of very old trees and other unique representatives of the flora and vegetation by designating them as living memorials.

4. The reintroduction of extinct plant species and restoration of phytocoenoses in the natural habitats.

5. The replacement of cultivated plant species and varieties in new habitats or botanical gardens.

6. The permanent maintenance of a definite percentage of woodland in the different regions of the country.

7. The organizing of lumbering, hay production, pasture, and gathering of medicinal plants in conformity with natural timber production capacity and vegetational growth.

These measures should be coordinated with the state program for: a) diminishing and ultimately eliminating the smog problem; b) elaborating programs for the protection of nature in every botanical region or district of the country; and c) re-establishing the natural balance in areas where it has been violated.

The observance of the requirements for preservation of the natural environment and the organization of concrete measures for this preservation are the responsibilities of specialized agencies. However, effective solutions to environmental problems and particularly the future relations between people and the flora and vegetation are possible only if they rest on a solid scientific foundation. In this respect, we have witnessed considerable delay, and only recently have we begun to build the base for a deeper systematic approach.

In view of this situation, Bulgarian botanical science should devote itself to the following tasks:

1. Establish and determine the botanical components of special importance for the aims of plant protection.

2. Determine the regimen and means of protection for these particular botanical components.

3. Efficiently control the way in which the different protection measures are put into practice.

The first task seems to be the most urgent. It is being addressed through several ongoing projects of the Institute of Botany: the Flora RP Bulgariceae, vegetation mapping, the Chromosome Atlas of Higher Plants, and the Vegetation Cover of Bulgaria.

Efforts should be directed to the protection of plants and phytocoenoses characteristic of particular regions and natural zones, of floristic diversity as a whole, and of the basic plant communities. The varied ecological conditions in this country demand variable standards for future vegetation restoration projects. The need to use our plant resources more efficiently should be met by taking greater advantage of our rich natural genetic resources, so as to favor natural selection within the ecosystems of Bulgaria and the natural evolutionary processes in the flora of the Balkan Peninsula.

These tasks demand urgent and intensive scientific studies. As already mentioned, various objects need to be protected by various management regimes and measures. Some measures will be trans-sectional in nature. Others, including the establishment of monitoring stations, will be more localized. All will need to be based on investigations of various ecological niches and their charac-teristics and inhabitants, either species or phytocoenoses. Monitoring stations in particular are needed to determine the nature of the changes - artificial or natural, progressive or regressive, adaptive or non-adaptive - at various locations over time. These studies require periodic inventory of the biological components on different levels of taxonomic and biological organization, as well as mapping methods that contribute to an understanding of their environmental dynamics (e.g., through phenological studies that reveal their seasonal plasticity).

Inseparable from immediate measures to protect and restore the natural environment, and particularly the flora and vegetation, are long-term measures intended to mobilize the whole nation and especially the youth. We need special efforts to educate the citizenry about the idea of nature protection - the permanent and multidirectional persuasion of the people that the natural plant resources are not inexhaustible and that their destruction is of extreme danger to human society.

Protection of Endemics

The populations of most Bulgarian endemics are relatively small and widely scattered. This has troubled Bulgarian botanists for some time (Stojanoff, 1934; Stefanoff and Kitanov, 1962). Later studies of the problem of the loss of native plant diversity (Kozuharov, 1975, 1977; Kuzmanov, 1978, 1981) focused on the protection of the most fragile part of Bulgarian flora - the endemic species and subspecies - based on our knowledge of their origins, population structures, and history.

The first concrete steps to protect endemic plants were taken in 1931, when the first Bulgarian reserve was established. Since then, about 400 protected natural areas have been created, among them 11 National parks and 89 reserves (including 17 biosphere reserves and 2 UNESCO world heritage sites). They include the Doupki-Dzhindzhiritsa Reserve in the Pirin Mountains; Alibotouch Reserve on Slavyanka Mountain; Koupena, Tchervenata Stena, Trigradsko Zdrelo, and Vasil Kolarov Reserves in the Rhodopes; Dzhendema Reserve in the central Stara Planina Mountains; Kaliakra Reserve on the northern Black Sea coast; Silkossia Reserve on Strandzha Mountain; Mariski Ezera and Parangalica Reserves in the Rila Mountains; and Torfeno Braniste on Vitosha Mountain. Among these are some of the most important biological "hotspots" and speciation centers in Bulgaria. However, the system of protected natural areas needs to be expanded to include more of the active speciation centers, to secure for the long-term the full diversity of the Bulgarian flora, and to provide greater stabilization to the Bulgarian ecosystems.

The problem lies in the manner in which these most fragile members of the plant communities should be protected. Some centers of speciation - for example, those within the alpine and the subalpine belts - can be included as links in a chain of reserves. This would allow opportunities for the automatic exchange of genetic material and the continual functioning of natural selection processes within them. Other reserves can be developed in areas where the primary plant communities have been replaced, and where people need to pay attention to retaining early successional stages (through, for example, occasional pasturing or mowing). Many species are adapted to a regular pattern of plowing and fallowing. Such are a number of annual, mainly cereal species, including wild wheat and barley. These and others may prove to be valuable sources of genetic material for their cultivated relatives. In short, protection of the gene pool of endemic and relict plants is of primary importance for the protection and restoration of the plant diversity that has developed in our country through the ages.

In 1952, twenty years after the first Bulgarian reserve was established, the Department for Environment Protection in the Ministry of Forests took steps to introduce legal measures for the protection of some species and the endemic genepool. Sixty-three species in the Bulgarian flora that were considered extremely rare and threatened were declared to be protected. Seventeen of these species are regional (Bulgarian and Balkan) endemics. Eight are Bulgarian endemics: Astracantha aitosensis (Ivanisch.) Podl., Daphne kosanini Stoj., Tulipa rhodopea (Vel.) Vel., Tulipa urumoffi Hay., Rheum raponticum L., Pulsatilla slavjankae (Zimm.) Jord. et Koz., Primula frondosa Janka, and Primula deorum Vel. Some highly local endemics have been included among the Balkan endemics, including Haberlea rhodopensis Friv., Ramonda serbica Panc., Viola delphinantha Boiss., Tulipa thracica Dav., Saxifraga stribrnyi Vel., Fritillaria drenovskii Deg., and Lilium rhodopaeum Delip.

The small number of endemics thus protected reflected the lack of information or knowledge of Bulgarian endemism at the time, as well as incomplete understanding of the reasons such measures were required. Among the threatened species listed, the greatest number belonged to the Scrophulariaceae, in the genera Verbascum (9 species) and Veronica (6); and the Liliaceae, in the genera Centaurea (5) and Tulipa (4). Among the rare species, the greatest number belonged to the genera Anthemis (6) and Alchemilla (5). With our increased understanding of endemism, it is now possible to revise the lists of officially protected species and to update the Red Data Book information on them.

Current and Potential Uses of Plant Resources

Many medicinal plants are the sole sources of raw materials for the pharmaceutical industry. More than 55 species of Bulgarian plants are used to produce extracts, other medical substances, and a range of medicines (nivaline, gluacine, vincarpane, reflavit, neutracid, ergotamine, cratemon, phytodont, etc.).

More than 100 types of tea, utilizing over 70 species of wild and cultivated medicinal Bulgarian plants, have been developed and approved. Species from the genera Rosa, Mathricaria, Valeriana, Melissa, Mentha, Crataegus, Tilia, among others, have been used in the preparation of these teas. Leucojum aestivum, Valeriana, Vinca, Claviceps purpurea, Verbascum nobile, Silybum marianum, Crataegus, and Artemisia are of the greatest economic significance.

About ten wild species are used as sources of ethereal oils, concretes, and absolue (including Geranium, Matricaria, Salvia, Mentha, Melissa). Other plants are widely used in the production of cosmetics, leathers, natural dyes, and other goods.

The genetic diversity of wild plants also holds great potential for future improvements in land use and for enlarging the cultivated flora. Genera that are important in this regard and that have definite economic significance as well include:

Forage plants

Fabaceae: Medicago, Trifolium, Esparseta, Vicia, Lathyrus

Poaceae: Festuca, Poa, Sesleria, Brachypodium, perennial species of Bromus

Fruit trees

Rosaceae: Pyrus, Rosa, Rubus

Plants rich in ethereal oils

Geraniaceae: Geranium, Erodium

Ranunculaceae: Ranunculus

Apiaceae: Chaerophyllum, Anthriscus, Seseli, Angelica

Lamiaceae: Mentha, Thymus, Saturea, Melissa, Salvia

Plants rich in alkaloids and glycosides

Ranunculaceae: Thalictrum, Adonis

Papaveraceae: Fumaria, Corydalis

Asteraceae: Achillea, Artemisia, Matricaria, Aster, Centaurea

Gentianaceae: Gentiana, Centhaurium

Scrophulariaceae: Verbascum

Vincaceae: Vinca

Ornamental plants

Volaceae, Asteraceae, Liliaceae, Scrophulariaceae, Boraginaceae

Plants for reforestation

Fagaceae: Quercus, Fagus, Carpinus

Aceraceae: Acer campestris, Acer pseudoplatanus

Salicaceae: Salix, Populus

Oleaceae: Fraxinus

Particularly suitable for the forage industry are many species from the following genera of Poaceae: Agrostis, Bromus, Festuca, Brachypodium, Phleum, Alopecurus, Poa, Briza, and Dactylis. Some foreign forms of these taxa have been cultivated already in Bulgaria, but they are not very well adapted to the specific environmental conditions of the country. Seed production of the Bulgarian forms of these taxa is necessary as well.

Some species from Fabaceae are of high forage quality. They are also an important source of genetic material for the improvement of the forage base. These species belong to the following genera: Anthylis, Esparseta, Trigonella, yellow perennial Medicago, Lathyrus, Mellilotus, Galega, and Trifolium. Many of these species are melliferous as well.

Some of the annuals have a very short vegetative growth period and are suitable for use as cover crops and green manures (e.g., Vicia, Pisum, Trifolium). These can provide more effective use and conservation of soil nutrients, moisture, and biota.

The many species of wild medicinal plants are of great interest in efforts to enlarge the variety of cultivated plants. Many of these plants have been gathered and used locally for centuries. Their supply in the wild, however, is limited - raising the question of their potential for cultivation. In fact, some of these have been cultivated already (e.g., Matricaria officinalis), but not as widely as necessary. Nearly 20 species from the following genera are suitable for cultivation: Rhamnus, Valeriana, Glycyrrhiza, Fumaria, Geranium, Rubia, Centhaurium, Centaurea, Viola, and Malva.

Many wild plants are highly suited for use in park ar-rangement, landscaping, and urban planting, as well as for pot flowers. This group includes over 70 species of plants from about 10 families (Araceae, Caryophyllaceae, Campanulaceae, Liliaceae, Paeoniaceae, Scrophulariaceae, Asteraceae, Violaceae, Iridaceae, Ranunculaceae).

Fragility

As noted above, the biological diversity of Bulgarian plants is threatened by a variety of forces, and these together determine the degree of ecosystem stability upon which the plants depend. If we consider fragility to increase as stability decreases, the following areas can be considered especially fragile.

Destabilization Due to Pollution

According to periodic assessments of the state of pollution in different regions of the country, the following zones can be considered to be particularly fragile. All are around large cities with industrial centers.

• Assenovgrad: metallurgic pollution near the Tchervenata Stena Reserve.
  
  
• Burgas: chemical works near lake ecosystems, sand complexes, and unique relict plant associations; one nearby national park and many reserves.
  
  
• Vratsa: chemical pollutants near unique habitats of endemic species; chemical pollution causing acid precipitation near habitats of rare and endemic species.
  
  
• Devnzha: chemical pollution near unique complexes of dense forests.
  
  
• Dimitrovgrad: chemical pollution with great negative effects on human populations and all components of the natural environment.
  
  
• Kurdzali: metallurgic and chemical pollution; a 700% increase in the lead content of the soil has been established; all ecosystems are threatened by impacts.
  
  
• Pernik: metallurgic pollution near a reserve with a high concentration of endemic and relict species.
  
  
• Plovdiv: metallurgic pollution as a result of which five species from the natural flora of the Thracian plain have disappeared.
  
  
• Russe: chemical and metallurgic pollution combined with transboundary transport of chlorine compounds; on the brink of total degradation of the natural vegetation.
  
  
• Sofia: chemical and metallurgic pollution near the Vitosha National Park.
  
  
• Vitosha Mountain: a particularly high degree of dust contamination.
  
  
• Srednogorie: metallurgic and chemical pollution; entire portions of the natural vegetation have been destroyed by local acid precipitation; the concentration of arsenic in the soil is 500% above the standard.

The ecosystems around these industrial centers are totally destabilized and thus can be regarded as particularly fragile. They require urgent aid.

Destabilization Due to Transboundary Pollution

Transboundary pollution is of special concern in three main regions: a) along the Danubian plain, as a result of the transport of pollutants from Romania; b) in the central Stara Planina Mountains as a result of the transport of pollutants from central Europe; and c) in the Strandzha Mountain region as a result of the transport of pollutants from Turkey.

Destabilization Due to Human Presence and Intensive Tourism

Human presence, and especially the occurrence of intensive tourism, is responsible for destabilization in the following ways and places:

• The state of the vegetation of the high peaks of the Pirin Mountains, the Rila Mountains, Vitosha Mountain, and Osogovo Mountain is very unstable due to the trampling of the meadows and contamination by tourist wastes.
  
  
• The state of the vegetation near water sources along the main tourist corridors is destabilized as a result of trampling of the meadows and tourist wastes.
  
  
• Sand dunes are used most intensively in the summer, which coincides with the period of maximum vegetative growth. That is why dune vegetation complexes are strongly affected, despite the fact that they lie largely within the boundaries of national parks and reserves.
  
  
• The natural conditions in the dense longose forests have been greatly modified as a result of changes in the water and salt regime. The number of herbaceous species in these forests has declined 30% in the last 10 years.

These kinds of habitats can be reconstructed if natural conditions are restored. This could be achieved in about 15 years.

Protected Areas

Almost all the most interesting habitats have been identified and protected to some degree. A few areas could be added to the existing network:

1. The habitats of many rare and threatened plants (about 15 species) concentrated eastwards from Targoviste near the village of Prolaz.

2. The habitat of Strandzha relics and endemics along the river Kovatch near the town of Malko Tarnovo.

3. The habitats of rare and threatened species (about 15 species) near the village of Bankzha and the town of Tran.

In addition, we recommend that the following specific actions be taken with regard to the protected areas:

1. Inventories of the protected sites should be completed and investigations of their natural genetic diversity undertaken.

2. Develop a ranger service in order to provide every reserve with effective protection.

3. Adopt taxes and fees for visits to the reserves to establish a fund for use in nature protection activities.

General Recommendations

We also offer the following more general recommendations:

1. Develop genecological analysis on the basis of available data and more active field work.

2. Complete the microtopographical mapping (1:20000) project.

3. Develop a national biomonitoring system for observation and management of the Natural parks and Reserves.

4. Establish a national information bank for the protected areas.

5. Create an independent agency for environmental protection.

Appendix 1. Species of Extinct, Threatened, and Rare Higher Plants in the Bulgarian Flora

Extinct

Aldrovanda vesiculosa L. Angelica archangelica L. Astragalus physocalyx Fisch. Caldesia parnassifolia (Bassi) Parl. Cardamine parviflora L. Carex rupestris Bell. ex All. Centaurea immanuelis-loewii Deg. Cynoglossum germanicum Jacq. Ferula orientalis L. Genista germanica L. Halimione portulacoides (L.) Aellen Hammarbia paludosa (L.) Kuntze Heleocharis carniolica Koch Hottonia palustris L. Hypericum setiferum Stef. Lathyrus pancicii (Juris.) Adam.

Linum pallasianum Schult. Liparis loeselii Rich. Lotus uliginosus Schkuhr Lysimachia thyrsiflora L. Onopordon brachteatum Boiss. et Heldr. Peucedanum palustre (L.) Moench Pimpinella major (L.) Huds. Rubus hercynicus G. Braun ex Focke Salix rosmarinifolia L. Scabiosa cosmoides Boiss. Tetragonolobus maritimus (L.) Roth Teucrium botrys L. Veronica euxina Turrill Vicia abbreviata Fisch. ex Spreng. Viola pumila Chaix

Threatened

Aegilops dichasians (Zhuk.) Humphries Aegilops pontica (Deg.) Waleff Aesculus hippocastanum L. Aethionema arabicum (L.) Andrs. ex Schulz Agropyron litorale (Host) Dum Alchemilla bandericensis Pawl. Alchemilla mollis (Buser) Rothm. Allium montanum F. W. Schmidt Alopecurus thracicus Penev et Koz. Androsace obtusifolia All. Anemone sylvestris L. Anthemis argyrophylla (Hal. et S. Georg.) Vel. Caragana frutex (L.) C. Koch Carex ferruginea Scop. Carex pirinensis (Acht.) Acht. Castanea sativa Mill. Centaurea amplifolia Boiss. et Heldr. Centaurea rupestris L. Centaurium maritimum (L.) Fritsch Cerastium velenovskyi Hayek Chamaecytisus ratisbonensis (Schaeff.) Rothm. Cladium mariscus (L.) R. Br. Colchicum borisii Stef. Colchicum davidovii Stef. Convolvulus elegantissimus Mill. Convolvulus holosericeus Bieb. Cortusa matthioli L. Corynephorus divaricatus (Pourr.) Breistr. Crassula tillaea Laster-Garl. Cressa cretica L. Cynoglossum rotatum Vel. Cypripedium calceolus L. Dianthus urumoffii Stoj. et Acht. Dracocephalum thymiflorum L. Dracunculus vulgaris Schott Elyna bellardii (All.) Koch Ephedra campylopoda C.A. Mey. Eriolobus trilobata Roem. Euphorbia allepica L. Euphorbia lucida Waldst. et Kit. Euphrasia drosocalyx Freyn Frankenia pulverulenta L. Fritillaria meleagroides Patrin Galanthus nivalis L. Galium rubioides L. Galium stojanovii Deg. Genista pilosa L. Gentiana acaulis L Gentiana lutea L. Gentiana punctata L. Goniolimon besserianum (Schult. ex Reichenb.) Kusn. Goniolimon tataricum (L.) Boiss. Herminium monorchis (L.) R. Br. Hippocrepis unisiliquosa L. Hippophae rhamnoides L. Hornungia procumbens (L.) Hayek Inula spiraeifolia L. Inula viscosa (L.) Aiton Isolepis supina (L.) R. Br. Laserpitium archangelica Wulf. Lathyrus montanus Bernh. Lathyrus saxatilis (Venth.) Vis. Lathyrus transsilvanicus (Spreng.) Fritsch Lens ervoides (Brign.) Grande Leucojum aestivum L. Ligularia sibirica (L.) Gass. Limonium asterotrichum (Salmon) Salmon Limonium latifolium (Sm.) O. Kuntze Limonium meyeri (Boiss.) O. Kuntze Vaccinium arctostaphylos L. Verbascum anisophyllum Murb. Verbascum boevae Stef.-Gat. Verbascum bugulifolium Lam. Verbascum davidoffii Murb. Verbascum dieckianum Borb. et Deg. Verbascum humile Janka Verbascum jankeanum Panc. Verbascum jordanovii Stef.-Gat. Verbascum juruc Stef.

Apium nodiflorum (L.) Lag. Apocynum venetum L Arabis collina Ten. Arabis nova Vill. Artemisia pedemontana Balbis Asplenium lepidum Presl Astragalus cornutus Pall. Astrodaucus litoralis (Bieb.) Drude Bromus lanceolatus Roth. Bupleurum longifolium L. Campanula versicolor Andrews Capsella thracica Vel. Carex disticha Huds. Matthiola odoratissima (Bieb.) R. Br. Medicago carstiensis Wulf. Menyanthes trifoliata L. Micromeria juliana (L.) Benth. ex Reichenb. Middendorfia borystenica (Schrank) Trautv. Minuartia mesogitana (Boiss.) Hand.-Mazz. Nuphar lutea (L.) Sibth. et Sm. Nymphaea alba L. Onosma rhodopaea Vel. Paeonia mascula (L.) Mill. Paeonia tenuifolia L. Pallenis spinosa (L.) Gass. Pancratium maritimum L. Peucedanum ruthenicum Bieb. Pleurospermum austriacum (L.) Hoffm. Polypodium australe Fee Pyracantha coccinea Roem. Pyrola rotundifolia L. Quercus mestensis Bond. et Gan. Quercus thracica Stef. et Ned. Rhododendron ponticum L. Rubus macrophyllus Weihe et Nees Rubus thyrsiflorus Weihe et Nees Ruta graveolens L. Salix pentandra L. Saxifraga aizoides L. Saxifraga androsacea L. Saussurea discolor DC. Sedum magellense Ten. Sedum zollicoferi Herm. et Stef. Sideritis taurica Steph. ex Willd. Sisymbrium polymorphum (Murr.) Roth. Sium sisarum L. Spiraea crenata L. Spiraea hypericifolia L. Spiraea salicifolia L. Syrenia cana (Paller et Mitterp.) Neilr. Taxus baccata L. Thalictrum foetidum L. Thelypteris palustris Schott Trachystemon creticum (Willd.) D. Don Trifolium ligusticum Balb. ex Loisel. Trifolium phleoides Pourr. ex Willd. Trifolium rubens L. Trifolium spumosum L. Trifolium squarrosum L. Trigonella spicata Sibth. et Sm. Tulipa aureolina Delip. Tulipa hageri Heldr. Tulipa rhodopaea Vel. Tulipa splendens Delip. Tulipa urumoffi Hayek Turgeniopsis foeniculacea (Fenzl.) Boiss. Utricularia minor L. Utricularia neglecta Lehm. Verbascum lagurus Fisch. et C.A.Mey. Verbascum nobile Vel. Verbascum pseudonobile Stoj. et Stef. Verbascum rupestre (Dav.) I.K.Ferguson Verbascum thracicum Vel. Verbascum urumovii Stoj et Acht. Veronica grisebachii S.M.Walters Veronica spicata L. subsp. velutina D. Peev Vicia amphicarpa Dorth.

Rare

Acanthus spinosus L. Acer heldreichii Orph. Achillea biebersteinii Afan. Achillea leptophylla Bieb. Achillea thracica Vel. Adiantum capillus-veneris L. Adonis microcarpa DC. Adonis wolgensis Stev. Aegilops speltoides Tausch Agropyron varnense (Vel.) Hayek Alchemilla achtarovii Pawl. Alchemilla anisiaca Wettst. Alchemilla asteroantha Rothm. Alchemilla bulgarica Rothm. Alchemilla catachnoa Rothm. Alchemilla erythropoda Juz. Alchemilla fissa Gunther et Schummel Alchemilla gracillima Rothm. Alchemilla grossidens Buser Alchemilla heterophylla Rothm. Alchemilla indivisa (Buser) Rothm. Alchemilla jumrukczalica Pawl. Alchemilla pawlowskii Assenov Alchemilla pirinica Pawl. Alchemilla plicatula Gand. Alchemilla pyrenaica Dufour Alchemilla straminea Buser Alchemilla viridiflora Rothm. Alkanna primuliflora Griseb. Alkanna stribrnyi Vel. Allium angulosum L. Allium cupanii Rafin. Allium stojanovii I.Kowatschev Alyssum cuneifolium Ten. Alyssum pulvinare Vel. Alyssum stribrnyi Vel. Amygdalus webbii Spach Anagallis minimus (L.) Krause Anchusa hybrida Ten. Anchusa stylosa Bieb. Andrachne telephioides L. Androsace hedraeantha Griseb. Athyrium alpestre (Hoppe) Rylands Aubrieta columnae Guss. Aubrieta gracilis Sprun. ex Boiss. Aubrieta intermedia Heldr. et Orph. ex Boiss. Barbarea bracteosa Guss. Barbarea stricta Andrz. Bartschia alpina L. Blackstonia perfoliata Huds. Brachypodium sanctum Janka Brassica jordanoffii O.E. Schultz Buglossoides glandulosa (Vel.) R. Fern. Bunium ferulaceum Sibth. et Sm. Bupleurum baldense Turra subsp. gussonei (Arc.) Tutin Bupleurum flavum Fors. Bupleurum fontanesii Guss ex Caruel Bupleurum Gerardii All. Cachrys alpina Bieb. Callitriche hamulata Kutz ex Koch Callitriche stagnalis Scop. Calluna vulgaris (L.) Salisb. Caltha cornuta Schott. Nym. et Kotschy Caltha polypetala Hochst. Calystegia soldanella (L.) R.Br. Campanula latifolia L. Campanula pusilla Hke. Campanula transsilvanica Schur ex Andrae Cardamine tuberosa Penzes et Vida Carduus rhodopaeus Vel. Carduus thracicus (Vel.) Hayek Carduus uncinatus Bieb. Carex distachya Desf. Carex heleonastes Ehrh. Carex limosa L. Carex punctata Gaud. Carum graecum Boiss. et Heldr. Carum multiflorum (Sibth. et Sm.) Boiss. subsp. strictum (Griseb) Tutin Celtis caucasica Willd. Centaurea achtarovii Urum. Centaurea arenaria Bieb. ex Willd. Centaurea atropurpurea Waldst. et Kit. Centaurea dubia Suter Centaurea gracilenta Vel. Centaurea inermis Vel. Centaurea kamciensis Kocev et Gancev Centaurea kernerana Janka Centaurea mannagettae Podp. Centaurea parilica Stoj. et Stef. Centaurea rumelica Boiss. Centaurium turcicum (Vel.) Ronn. et Fritsch Cerastium gracile Duf. Ceratophyllum muricatum Cham. Cercis siliquastrum L. Chamaecytisus danubialis ((Vel.) Rothm. Chamaecytisus frivaldszkyanus (Deg.) Kuzm. Chamaecytisus kovacevii (Vel.) Rothm. Echinophora sibthorpiana Guss. Echium plantagineum L. Edraianthus serbicus (Kern.) Petr. Elatine alsinastrum L. Elatine triandra Schkuhr Empetrum nigrum L. Epimedium pubigerum (DC.) Morren et Decne Eranthis bulgaricus (Stef.) Stef. Erica arborea L. Erigeron vichrensis Pawl. Erodium absinthoides Willd. subsp. elatum (Form.) Davis et Robertis Erodium hoefftianum G.A. Mey. Eryngium creticum Lam. Eryngium maritimum L. Eryngium palmatum Panc. et Vis. Erysimum comatum Panc. Erysimum cheiranthoides L. Euphorbia paralias L. Euphorbia peplis L. Ferula heuffelii Griseb. Festuca callieri (Hack.) Markgr. Festuca pirinica Horvat ex Markgr.-Dannenb. Festuca rupicola Heuff. Festuca vaginata Waldst. et Kit. ex Willd. Festuca xanthina Roem. et Schult. Fibigia clypeata (L.) Medic. Ficus carica L. Fritillaria drenovskyi Deg. et Stoj. Fritillaria graeca Boiss. et Sprun. Fritillaria orientalis Adams (= Tenella) Fritillaria pontica Wahl. Fritillaria stribrnyi Vel. Fumaria thuretii Boiss. Galium boreale L. Galium bulgaricum Vel. Galium procurrens Ehrend. Galium rhodopaeum Vel. Gaudinia fragilis (L.) Beauv. Gentiana frigida Haenke Gentianella amarella (l.) Born. Gentianella crispata (Vis.) Holub Gentianella engadinensis (Wettst.) Holub Gentianella praecox (A. et J.Kern.) Dostal Geranium bohemicum L. Geranium caeruleatum Schur Geranium macrostyllum Boiss. Geranium tuberosum L. Geum bulgaricum Panc. Geum rhodopaeum Stoj. et Stef. Globularia trichosantha Fisch. et C.A.Mey. Glycyrrhiza glabra L. Goniolimon dalmaticum (C.Presl) Reichenb. fil. Goodiera repens (L.) R.Br. Groenlandia densa (L.) Fourr. Gypsophila tekirae Stef. Linum uninerve (Roch.) Borb. Lithospermum sibthorpianum Griseb. Lloydia serotina (L.) Reichenb. Logfia gallica (L.) Cosson Lotononis genistoides (Fenzl..) Benth. Ludwigia palustris (L.) Elliot Lupinus albus L. Luzula deflexa Koz. Malcolmia angulifolia Boiss. et Orph. Malcolmia serbica Panc. Maresia nana (DC.) Batt. Marrubium frivaldskyanum Boiss. Marsilea quadrifolia L. Medicago constricta Dur. Medicago coronata (L.) Bart. Medicago litoralis Rhode ex Loisel. Medicago rhodopaea Vel. Melampyrum bihariense A. Kern. Melica altissima L. Merendera rhodopaea Vel. Merendera sobolifera C.A. Mey. Mespilus germanica L. Meum athamanticum Jacqu. Micromeria frivaldskyana (Deg.) Vel. Micropyrum tenellum (L.) Link Minuartia diljanae P. Pan. Minuartia rhodopaea (Deg.) Koz. et Kuzm. Minuartia mediterranea (Lebed.) K. Maey Minuartia rumelica P. Pan. Minuartia saxifraga (Friv.) Graebn. Minuartia stojanovii (Kitan.) Koz. et Kuzm. Moehringia grisebachii Janka Moehringia jankae Griseb. Morina persica L. Nepeta parviflora Bieb. Nepeta ucranica L. Nigella orientalis L. Nonnea obtusifolia (Willd.) DC. Nymphoides peltata (S.G. Gmel.) O. Kuntze Oenanthe angulosa Griseb. Oenanthe lachenalii Gmel. Oenanthe millefolia Janka Oenanthe pimpinelloides L. Oenanthe tenuifolia Boiss. et Orph. Ononis adenotricha Boiss. Ononis repens L. Onosma aucherianum DC. Opopanax chironium (L.) Koch Orchis globosa L. Orchis militaris L. Orchis papilionacea L. Orchis provincialis Balb. Orobanche serbica Beck. et Petr. Otanthus maritimus (L.) Hoffm. et Link Oxytropis urumovii Jav. Papaver degenii (Urum. et Jav.) Kuzm. Ranunculus stojanovii Delip. Reichardia picroides (L.) Roth Rhamnus alpinus L. Rheum rhaponticum L. Rhinanthus javorkae Soo Rhododendron myrtifolium Schott et Kotschy Rhynchocorys elephas (L.) Griiseb. Ribes nigrum L. Rindera umbellata (Waldst. et Kit.) Bge. Romulea bulbocodium (L.) Seb. et Mauri Rubus oblongoobovatus Mark. Rubus vepallidus Sudre Saccharum ravennae (L.) Murrey Sagina maritima G. Don. Salix hastata L. Salix retusa L. Salvia forskaohlei L. Salvia scabiosifolia Lam. Salvia verbenaca L. Samolus valerandii L. Saponaria stranjensis D. Jord. Satureja rumelica Vel. Saxifraga ferdinandii-coburgi Kell. et Sund. Saxifraga marginata Sternb. Saxifraga mollis Sm. Saxifraga retusa Gouan Saxifraga spruneri Boiss. Saxifraga stribrnyi (Vel.) Podp. Scabiosa atropurpurea L. Scabiosa rhodopensis Stoj. et Stef. Scandix australis L. Schoenus ferrugineus L. Scilla bithnica Boiss. Scorpiurus subvillosus L. Scorzonera parviflora Jacq. Scrophularia laciniata Waldst. et Kit. Secale rhodopaeum Delip. Secale sylvestre Host Sedum aetnense Tineo Sedum kostovii Stef. Sedum stefco Stef. Sedum tchernokolevii Stef. Sempervivum ciliosum Graibn. Sempervivum velenovskyi Ceschm. Senecio doria L. Senecio paludosus L. Senecio pancici Deg. Senecio umbrosus Waldst. et Kit. Serapias vomeracea (Burm.) Briq. Serratula bulgarica Acht. et Stoj. Seseli bulgaricum Ball Seseli degenii Urum. Seseli rhodopaeum Vel. Sesleria alba Sibth. et Sm. Trinia glauca (L.) Dumort. subsp. carniolica (Kern.) H.Wolff Trinia ramosissima (Fisch. ex Trev.) Koch. subsp. longipes (Borb.) Soo Trollius europaeus L. Turritis pseudoturritis (Boiss. et Heldr.) Vel. Thypha shuttleworthii Koch et Sond. Urospermum picroides (L.) F.W.Smidt Utricularia vulgaris L. Valeriana dioscoridis Sibth. et Sm. Valeriana montana L. Valeriana simplicifolia (Reichenb.) Kabath. Valerianella bulgarica Vel. Valerianella eriocarpa Desv. Verbascum adrianopolitanum Podp. Verbascum decorum Vel. Verbascum eriophorum Godr. Verbascum purpureum (Janka) Hub.-Mor. Verbascum roripifolium (Hal.) I.K.Ferguson Verbena supina L. Veronica austriaca L. subsp. neicevii (Deg.) D.Peev Veronica austriaca L. subsp. tenuissima Deg. et Dren. Veronica chamaedrys L. subsp. krumovii D. Peev

Anemone narcissiflora L. Anethum graveolens L. Angelica pancicii Vand. Anthemis auriculata Boiss. Anthemis gaudium-solis Vel. Anthemis jordanovii Stoj et Acht. Anthemis macrantha Heuff. Anthemis orbelica Panc. Anthemis regis-borisii Stoj. et Acht. Anthemis rumelica (Vel.) Stoj. et Acht. Anthemis sancti-johannis Stoj., Steff. et Turrill Anthemis stribrnyi Vel. Anthemis virescens Vel. Aquilegia aurea Janka Aquilegia vulgaris L. Arabis allionii DC. Arabis ferdinandi coburgii Kell. et Sund. Arabis jacquinii Beck Arabis muralis Bertol. Arctostaphylos uva-ursi (L.) Spreng. Arenaria pirinica Stoj. Arenaria rhodopaea Delip. Arenaria rigida Bieb. Argusia sibirica (L.) Dandy Aristolochia rotunda L. Armeria alpina Willd. Artemisia eriantha Ten. Artemisia lerchiana Weber Artemisia pontica L. Asperula capitata Kit. ex Schultes Asperula involucrata Wahlenb. Asperula suberosa Sibth. et Sm. Asplenium cuneifolium Viv. Asterolinon linum-stellatum (L.) Duby Astragalus aitossiensis Ivanisch. Astragalus centralpinus Br.-Bl. Astragalus excapus L. Astragalus fraxinifolius DC. Astragalus sesameus L. Astragalus thracicus Griseb. Astragalus wilmottianus Stoj. Asyneuma kellerianum Stef. Atropa belladonna L. Chamaecytisus neicefii (Urum.) Rothm. Cheilanthes persica (Bory) Mett. ex Kuhn Chondrilla urumovii Deg. Cicer montbretii Jaub. et Spach Cicuta virosa L. Circaea alpina L. Cirsium alatum (S.G.Gmelin) Bobrov Cirsium bulgaricum DC. Cirsium oleraceum (L.) Scop. Cistus salvifolius L. Clematis alpina (L.) Mill. Cleome ornithopodioides L. Colchicum bivonae Guss. Colchicum diampolis Delip. et Ceschm. Colchicum rhodopaeum I. Kovatschev Convolvulus compactus Boiss. Convolvulus lineatus L. Convolvulus suendermannii Bornm. Corispermum marschalii Stev. Corispermum nitidum Kit. Crambe tataria Sebeok Crepis bithynica Boiss. Crepis nicaeensis Balbis Crepis schachtii Baebcok Crepis stojanovii Georg. Crithmum maritimum L. Crocus olivieri J. Gay Crocus tommasinianus Herb. Crucianella latifolia L. Cryptogramma crispa (L.) R.Br. Cyclamen coum Mill. Cystopteris regia (L.) Presl Danthoniastrum compactum (Boiss. et Heldr.) Holub Daphne blagayana Freyer Daphne cneorum L. Daphne kosanini (Stoj) Stoj. Daphne laureola L. Daphne oleoides Schreb. Daphne pontica L. Delphinium albiflorum DC. Delphinium halteratum Sibth. et Sm. Delphinium peregrinum L. Dianthus carthusianorum L. Dianthus drenowskianus Rech. fil. Dianthus kladovanus Degen Dianthus nardiformis Janka Dianthus stribrnyi Vel. Digitalis laevigata Waldst. et Kit. Diphasium alpinum (L.) Rothm. Diphasium complanatum (L.) Rothm. Diplachne bulgarica Bornm. Draba athoa (Griseb.) Boiss. Draba carinthiaca Hoppe Draba tomentosa Claivr. Drosera rotundifolia L. Driopteris villarii (Bell.) Woyn ex Schinz et Thell. Gypsophila trichotoma Wend. Haberlea rhodopensis Friv. Halimione pedunculata (L.) Aellen Haplophyllum balcanicum Vand. Haplophyllum thesioides Pall. Hedysarum grandiflorum Pall. Hedysarum tauricum Pall. ex Willd. Heptaptera triquetra (Vent.) Tutin Heracleum angustisectum (Stoj. et Acht.) D. Peev Hesperis macedonica Adam. Hesperis theophrasti Borb. Hieracium stefanoffii Zahn Hippomarathrum cristatum (DC.) Boiss. Hippuris vulgaris L. Huetia cynapioides (Guss.) Ball Hymenocarpus circinatus (L.) Savi Hypecoum ponticum Vel. Hypericum androsaemum L. Hypericum boissieri Petr. Hypericum calycinum L. Hypochaeris cretensis (L.) Ch. et B. Ilex aquifolium L. Isoetes setaceae Lam. Juncus acutiflorus Ehrh. Juncus ranarius Song. et Perr. Juncus triglumis L. Juniperus sabina L. Jurinea ledebourii Bunge Jurinea tzar-ferdinandii Dav. Kentranthus kellereri Stoj. et Stef. Kernera saxatilis (L.) Reichenb. Koeleria brevis Stev. Lamium bifidum Cyr. Laserpitium krapfii Grantz. Laserpitium siler L. Lathrea rhodopaea Dingler Lathyrus grandiflorus Sibth. et Sm. Lathyrus palustris L. Legouzia pentagonia Thell. Lemna gibba L. Leontodon riloensis Hayek Leontopodium alpinum Gass. Lepidotis inundata (L.) C. Born. Lepidotrichum uechtritzianum (Bornm.) Vel. Ligularia glauca (L.) O. Hoffm. Lilium albanicum Griseb. Lilium jankae Kern. Lilium rhodopaeum Delip. Limodorum abortivum (L.) Sw. Limonium gmelinii (Willd.) O. Kuntae Limonium vulgare Mill. Lindernia procumbens (Krock.) Philcox Linum elegans Sprun. ex Boiss. Linum extraaxillare Kit. Linum tauricum Willd. subsp. bulgaricum (Podp.) Petrova Parapholis incurva (L.) C.E. Hubb. Pastinaca umbrosa Stev. ex DC. Pedicularis oederi Vahl. Pedicularis palustris L. Peplis alternifolia Bieb. Petasites kablickianus Tausch ex Berchtold Petkovia orphanidea (Boiss.) Stef. Petrorhagia alpina (Habl.) Ball et Heywood Petrorhagia tessala (Boiss.) Ball et Heywood Petrosimonia brachiata (Pall.) Bunge Peucedanum olygophyllum (Griseb.) Vand. Peucedanum vittijugum Boiss. Phalaris tuberosa L. Phyteuma confusum Kern. Plantago bellardii All. Plantago cornuti Gouan Plantago tenuiflora Waldst. et Kit. Platanus orientalis L. Poa aitosensis Koz. et Stoeva Poa pirinica Stuj. et Acht. Polycnemum heuffelii Lang. Polygala acarnanica (Chodat) Koz. et Petrova Polygala alpestris Reichenb. Polygala amarella Grantz Polygala carniolica Kern. Polygala hospita Heuff. Polygala monspeliaca L. Polygala rhodopaea (Vel.) Janch. Polygala supina Schreb. Potamogeton mucronatus Schrad. ex Sond. Potamogeton praelongus Wulf. Potamogeton trichoides Cham. et Schlecht. Potentilla apenina Ten. Potentilla chrysantha Trevir. Potentilla emili-popii Nyarady Potentilla fruticosa L. Potentilla montenegrina Pant. Potentilla nicici Adam. Potentilla palustris (L.) Scop. Prangos ferulacea (L.) Lindl. Primula deorum Vel. Primula frondosa Janka Primula halleri G.F. Gmel. Primula vulgaris Huds. subsp. sibthorpii (Hoffm.) Smith. et Forest Pulmonaria mollissima Kern. Pulsatilla halleri (All.) Willd. Pulsatilla pratensis (L.) Mill. Pulsatilla slavjankae (Zimm.) D. Jord. et Koz. Pulsatilla vernalis (L.) Mill. Pyrola media Swartz Pyrus bulgarica Khutath. et Sachok. Quercus coccifera L. Quercus hartwissiana Stev. Ramonda serbica Panc. Ranunculus sphaerospermus Boiss. et Blanche Sibbaldia procumbens L. Sideritis lanata L. Sideritis scardica Griseb. Silaum silaus (L.) Schinz et Thell. Silene alpina (Lam.) Thomas Silene caliacrae D. Jord. et P. Panc. Silene chlorantha (Willd.) Ehrh. Silene cretica L. Silene euxina Rupr. Silene graeca Boiss. et Sprun. Silene heuffelii Soo Silene nutans L. Silene perinica Hayek Silene velcevii D.Jord. et P.Pan. Silene velenovskyana D.Jord. et P.Pan. Sison amomum L. Smyrnium rotundifolium Mill. Soldanella carpatica Vierch. Sonchus palustris L. Sparganium affine Schnizl. Sparganium minimum Wallr. Spiranthes automnalis Rich. Stachys arenariaeformis Rouy Stachys balcanica Ball. Stachys bulgarica (Deg. et Neic.) Hayek Stachys maritima Gouan. Stachys scardica (Griseb.) Hayek Stachys serbica Panc. Stachys thracica Dav. Stefanoffia daucoides (Boiss.) H. Wolff Stipa lessingiana Trin. et Rupr. Stratiotes aloides L. Streptopus amplexifolius (L.) DC. Subularia aquatica L. Sueda heterophylla (Kar. et Kit.) Bunge ex Boiss. Symphyandra wanneri (Rochel) Heuff. Symphytum tauricum Willd. Taraxacum bessarabicum (Horn.) Hand.-Mazz. Taraxacum bithynicum DC. Taraxacum hoppeanum Griseb. Taraxacum megalorrhizon (Forsk.) Hand.-Mazz. Teucrium lamiiolium D'Urv. Theligonum cynocrambe L. Thesium linophyllon L. Thymus nikolovii (Deg. et Urum.) Stoj. et Stef. Thymus perinicus (Vel.) Stoj. Stef. et Kit. Tilia rubra DC. Trachelium jacuinii (Sieber) Boiss. Thrachystemon orientalis (L.) D. Don Tragopogon balcanicus Vel. Tragopogon stribrnyi Hayek Trapa natans L. Trifolium constantinopolitanum Ser. Trifolium globosum L. Trifolium physodes Stev. ex Bieb. Trifolium spumosum L. Veronica kellererii Deg. et Urum. Veronica rhodopaea (Vel.) Deg. ex Stoj. et Stef. Veronica turrilliana Stoj. et Stef. Vicia barbazitae Ten. et Guss. Vicia dumetorum L. Vicia incisa Bieb. Vicia pisiformis L. Vicia truncatula Fisch. ex Bieb. Viola balcanica Delip. Viola delphynantha Boiss. Viola gracilis Sibth et Sm. Viola grisebachiana Vis. Viola orbelica Panc. Viola orphanidis Boiss. Viola palustris L. Viola perinensis Becker Viola pyrenaica Ramond ex DC. Viola rhodopeia Becker Viola speciosa Pant. Viola stojanowii Becker Vulpia bromoides (L.) S.F.Gray Vulpia unilateralis (L.) Stace Wolffia arrhiza (L.) Hork. ex Wimmer

Appendix 2. Pteridophyte Species in the Red Data Book

Adiantum capillus-veneris L. Asplenium cuneifolium Viv. Asplenium lepidum C. Presl Athyrium distentifolium Opiz Cheilanthes persica (Bory) Mett. et Kuhn Cryptogramma crispa (L.) R. Br. Cystopteris alpina (Lam.) Desv. Diphasiastrum alpinum (L.) Holub	Diphasiastrum complanatum (L.) Holub Dryopteris pallida (Bory) Maire et Petitm. Isoetes lacustris L. Lycopodiella inundata (L.) Holub Marsilea quadrifolia L. Osmunda regalis L. Polypodium cambricum L. Thelypteris palustris Schott.

Appendix 3. Pteridophyte Species Protected By Law

Adiantum capillus-veneris L. Asplenium cuneifolium Viv. Diphasiastrum complanatum (L.) Holub Lycopodiella inundata (L.) Holub

Marsilea quadrifolia L. Osmunda regalis L. Polypodium cambricum L.

Appendix 4. Species of Endemic, Relict, Rare, and Threatened Plants in the Strandzha Mountain Region of Southeast Bulgaria

Local Endemics
Anthemis jordanovii Stoj et Acht. Saponaria stranjensis D. Jord.	Veronica turrilliana Stoj. et Stef
Relicts (Tertiary)
Acer campestre L. Acer tataricum L. Alnus glutinosa (L.) Gaertn. Carpinus betulus L. Carpinus orientalis Mill. Celtis austriaca L. Celtis caucasica Willd. Clematis vitalba L. Corylus avelana L. Cotinus coggygria Scop. Daphne pontica L. Fagus orientalis Lipsky Fraxinus ornus L. Hedera helix L. Ilex colchica Lonicera etrusca Santi Mespilus germanica L.	Phyllirea media L. Populus tremula L. Prunus laurocerasus L. Pyracantha coccinea Roem. Quercus cerris L. Quercus daleschampii Ten. Quercus hartwissiana Stev. Rhododendron ponticum L. Salix alba L. Salix caprea L. Smilax excelsa L. Taxus baccata L. Trapa natans L. Ulmus laevis Pall. Vaccinium arctostaphyllos L. Viscum album L.
Balkan endemics
Anchusa thessala Boiss. et Sprun. Asphodeline liburnica Rchb. Centaurea amplifolia Boiss. et Heldr. Comandra elegans Rchb. Crocus biflorus Mill. Genista rumelica Vel. Lepidotrichum uechtritzianum (Bornm.) Vel. Oenanthe tenuifolia Boiss. et Orph.	Onobrychis alba (W.K.) Desv. Onobrychis calcarea Vandas Orobanche esulae Panc. Silene thymifolia Sibth. et Sm. Trifolium dalmaticum Vis. Verbascum adrianopolitanum Podp. Veronica turrilliana Stoj. et Stef.
Endangered
Apocynum venetum L. Astragalus litoralis (M.B.) Drude Euphorbia lucida W.K. Goniolimon besseranum (Schult. ex Rchb.)Kuzn. Goniolimon tataricum (L.) Boiss. Leucojum aestivum L. Nuphar lutea (L.) S. et S.	Nymphaea alba L. Paeonia tenuifolia L. Pancratium maritimum L. Pyracantha coccinea Roem. Rhododendron ponticum L. Trachystemon orientalis (L.) D.Don. Tulipa thracica Dav.
Threatened by extinction
Andrachne telephioides L. Argusia sibirica (L.) Dandy Calysdegia soldanella (L.) R.Br. Centaurea arenaria Bieb. ex Willd. Cicer montbretii Jaub. et Spach	Hedysarum tauricum Pall. ex Willd. Heptaptera triquetra (Vent.) Tutin Hypecoum ponticum Vel. Lemna gibba L. Logfia gallica (L.) Cosson et Germ Medi

Appendix 5. Species of Extinct, Threatened, and Rare Plants of the Rila Mountains of Southwest Bulgaria

Extinct
Anthemis macrantha Heuff. ** Carex rupestris Bell. ex All. * Hypecoum ponticum Vel. ** Lathraea rhodopaea Dingler ** Limodorum abortivum (L.) Sw. ** Orchis militaris L. ** Pedicularis palustris L. ** Pleurospermum austriacum (L.) Hoffm. *	Primula halleri G.F.Gmel. ** Rubus hercynicus G. Braun ex Focke* Silene velenovskyana D.Jord. et P.Panov ** Vicia abbreviata Fisch. ex Spreng. subsp. orbelica (Stoj. et Stef.) Kuzm. * Vicia truncatula Fish. ex Bieb. * extinct from Bulgarian flora totally ** extinct only from Rila Flora
Endangered
Alyssum pulvinare Vel. Anemone narcissiflora L. Anemone sylvestris L. Anthemis orbelica Panc. Anthemis sancti-johannis Stoj., Steff. et Turrill Aquilegia aurea Janka Aquilegia vulgaris L. Arabis allionii DC. Athyrium alpestre (Hoppe) Rylands Aubrieta gracilis Sprun. ex Boiss. Artemisia eriantha Ten. Barbarea bracteosa Guss. Centaurea kernerana Janka Cicerbita plumeri (L.) Kirschl. Clematis alpina (L.) Mill. Cryptogramma crispa (L.) R.Br. Cystopteris regia (L.) Presl Diphasium alpinum (L.) Rothm. Draba carinthiaca Hoppe Drosera rotundifolia L. Galanthus nivalis l. Gentiana lutea L. Gentiana punctata L. Geum bulgaricum Panc. Juncus triglumis L. Juniperus sabina L. Lepidotis inundata (L.) Born. Leontodon riloensis Hayek Ligularia glauca (L.) O. Hoffm. Lilium jankae Kern. Lloydia serotina (L.) Reichenb. Lolium remotum Sehr. Luzula deflexa Koz. Menyanthes trifoliata L. Minuartia saxifraga (Friv.) Graebn.	Myosotis orbelica (Vel.) N.Andr. et D.Peev Montia sibirica (L.) Howell Potamogeton praelongus Wulf. Potentilla montenegrina Pant. Pulsatilla vernalis (L.) Mill. Quercus mestensis Bod. et Ganc. Rheum rhaponticum L. Rubus melanoxilon Mueller et Wirtg. Rubus pectinatus Sudre et Gravet Salix hastata L. Salix retusa L. Saussurea discolor (Willd.) DC. Saxifraga androsacea L. Saxifraga carpatica Reichenb. Saxifraga retusa Gouan Sedum kostovii Stef. Sedum stefco Stef. Sempervivum ciliosum Graibn. Sempervivum velenovskyi Ceschm. Sorbus aucuparia L. subsp. fenenkiana Georg. et Stoj. Sparganium affine Schnizl. Spiranthes autumnalis Rich. Streptopus amplexifolius (L.) DC. Subularia aquatica L. Taraxacum bithynicum DC. Taxus baccata L. Thlaspi praecox Wulf. subsp. cuneifolium (Griseb.) Clapham. Tragopogon balcanicus Vel. Trollius europaeus L. Turritis pseudoturritis (Boiss. et Heldr.) Vel. Verbascum jankaeanum Panc. Veronica fruticosa L. Vicia amphicarpa Dort.
Rare
Aconitum firmum Reichenb. Acer heldreichii Orph. Alchemilla fissa Gunter et Schummel Alchemilla garcensis Pawl. Alchemilla pyrenaica Dufour Alchemilla reniformis Busser Anagallis minimus (L.) Krause Androsace hedraeanthea Griseb. Angelica pancicii Vand. Arctium nemorosum Lej. Arctostaphyllos uva-ursi (L.) Spreng. Armeria alpina Willd. Astragalus australis (L.) Lam. Asyneuma trichocalycinum (Ten.) K. Maly Atropa belladonna L. Bartschia alpina L. Bupleurum Gerardii All. Callitriche hamulata Kutz ex Koch Carum multiflorum (Sibth. et Sm.) Boiss. subsp. strictum (Griseb) Tutin Chaerophyllum bulbosum L. Cheilanthes maranthae (L.) Domin Coralliorrhiza trifida Chatel. Dryopteris dilatata (Hoffm.) A.Gray. Empetrum nigrum L. Euclidium syriacum R. Br. Fritillaria scorpilii Vel. Galium boreale L. Gentiana frigida Haenke Gentianella engadinensis (Wettst.) Holub Geranium bohemicum L. Geranium reflexum L. Geum reptans L. Herniaria glabra L. Herniaria nigrimontium FR. Hermann Hieracium sericophylum Neic. et Zahn. Hieracium trebevicianum K.Maly Lathyrus grandiflorus Sibth. et Sm. Listera cordata (L.) R.Br. Minuartia recurva (All.)Schinz et Thell subsp. orbelica (Vel.) Graebn.	Alchemilla catachnoa Rothm. Alchemilla erythropoda Juz. Alchemilla gracillima Rothm. Alchemilla pawlowskii Assenov Oxytropis campestris (L.) DC. Pedicularis hoermanniana K.Maly Pedicularis oederi Vahl. Peucedanum olygophyllum (Griseb.) Vand. Potentilla regis-borisii Stoj. Primula deorum Vel. Primula farinosa L. subsp. exigua Vel. Pyrola media Swartz Rhododendron myrtifolium Schott et Kotschy Rhodiola rosea L. Rosa mollis Sm. Saxifraga adscendens L. subsp. discolor (Vel.) Kuzm. Senecio nemorensis L. subsp. bulgaricus (Vel.) Koz. et N.Andr. Senecio pancici Deg. Seseli rigidum W.K. subsp. puberula D.Peev Sibbaldia procumbens L. Silene heuffelii Soo Silene pusilla W.K. Soldanella carpatica Vierch. Stellaria palustris Retz. Symphyandra wanneri (Rochel) Heuff. Swertia perennis L. Thymus heterotrichus Griseb. Trifolium bulgaricum Schreb. subsp. badium Trifolium nigrescens Viv. subsp. nigrescens Utricularia vulgaris L. Valeriana montana L. Veronica kellererii Deg. et Urum. Veronica rhodopaea (Vel.) Deg. ex Stoj. et Stef. Vicia dumetorum L. Vinca major L. subsp. balcanica (Penzes) Koz. et Petr. Viola orbelica Panc. Viola rhodopeia Becker.

Appendix 6. Species of Endangered and Rare Plants in the Pirin Mountains of Southwest Bulgaria

Endangered
Alchemilla bandericensis Pawl. Anemone sylvestris L. Brassica jordanovii O.E.Schultz Carex ferruguinea Scop. Carex pirinensis (Acht.) Acht. Castanea sativa Mill. Elyna bellardii (All.) Koch Euphrasia drosocalyx Freyn Galanthus nivalis L. Galium stojanovii Deg.	Gentiana lutea L. Gentiana punctata L. Goniolimon tataricum (L.) Boiss. Laserpitium archangelica Wulf. Ligularia sibirica (L.) Cass. Menyanthes trifoliata L. Taxus baccata L. Trigonella spicata Sibth. et Sm. Utricularia minor L. Verbascum davidoffii Murb.
Rare
Alchemilla bulgarica Rothm. Alchemilla pirinica Pawl. Alkanna stribrnyi Vel. Anemone narcissiflora L. Aquilegia aurea Janka Arabis allionii DC. Arabis ferdinandi coburgii Kell. et Sund. Arabis jaquinii Beck Arabis muralis Bertol. Arctostaphyllos uva-ursi (L.) Spreng. Arenaria pirinica Stoj. Aristolochia rotunda L. Armeria alpina Willd. Artemisia eriantha Ten. Asperula suberosa Sibth. et Sm. Astragalus fraxinifolius DC. Astragalus sesameus L. Asyneuma kellererianum Stef. Aubrieta columnae Guss. Aubrieta gracilis Sprun. ex Boiss. Barbarea bracteosa Guss. Bartschia alpina L. Brassica jordanoffii O.E. Schultz Callitriche hamulata Kutz ex Koch Campanula latifolia L. Campanula transsilvanica Schur ex Andrae Carum graecum Boiss. et Heldr. Centaurea achtarovii Urum. Cryptogramma crispa (L.) R.Br. Daphne cneorum L. Daphne kosanini (Stoj) Stoj. Daphne oleoides Schreb. Diphasium alpinum (L.) Rothm. Draba carinthiaca Hoppe Drosera rotundifolia L. Dryopteris villarii (Bell.) Woyn ex Schinz et Thell. Empetrum nigrum L. Erigeron vichrensis Pawl. Festuca pirinica Horvat ex Markgr.-Dannenb. Fritillaria drenovskyi Deg. et Stoj. Fritillaria orientalis Adams (= Tenella) Gentiana frigida Haenke Gentianella engadinensis (Wettst.) Holub Geranium macrostyllum Boiss. Heracleum angustisectum (Stoj. et Acht.) D. Peev Hieracium stefanoffii Zahn Isoetes setaceae Lam. Kentranthus kellereri Stoj. et Stef. Kernera saxatilis (L.) Reichenb.	Leontodon riloensis Hayek Leontopodium alpinum Gass. Lilium jankae Kern. Linum elegans Sprun. ex Boiss. Medicago constricta Dur. Minuartia rhodopaea (Deg.) Koz. et Kuzm. Minuartia saxifraga (Friv.) Graebn. Minuartia stojanovii (Kitan.) Koz. et Kuzm. Ononis adenotricha Boiss. Oxytropis urumovii Jav. Papaver degenii (Urum. et Jav.) Kuzm. Petasites kablickianus Tausch ex Berchtold Petkovia orphanidea (Boiss.) Stef. Petrorhagia alpina (Habl.) Ball et Heywood Petrorhagia tessala (Boiss.) Ball et Heywood Poa pirinica Stoj. et Acht. Polygala amarella Grantz Polygala monspeliaca L. Polygala rhodopaea (Vel.) Janch. Potentilla apenina Ten. Primula halleri G.F.Gmel. Pulmonaria mollissima Kern. Pyrola media Swartz Rhamnus alpinus L. Rhinanthus javorkae Soo Rhynchocorys elephas (L.) Griseb. Saxifraga ferdinandii-coburgi Kell. et Sund. Saxifraga spruneri Boiss. Saxifraga stribrnyi (Vel.) Podp. Scrophularia laciniata Waldst. et Kit. Sedum kostovii Stef. Sempervivum ciliosum Graibn. Senecio pancici Deg. Sibbaldia procumbens L. Sideritis scardica Griseb. Silene velenovskyana D.Jord. et P.Pan. Subularia aquatica L. Taraxacum bithynicum DC. Thymus perinicus (Vel.) Stoj. Stef. et Kit. Tragopogon balcanicus Vel. Trollius europaeus L. Utricularia vulgaris L. Veronica austriaca L. subsp. tenuissima Deg. et Dren. Veronica kellererii Deg. et Urum. Viola grisebachiana Vis. Viola orbelica Panc. Viola pyrenaica Ramond ex DC.

Appendix 7. Species of Plants Rich in Ethereal Oils

Acorus calamus L. Anethum graveolens L. Angelica sylvestris L. Apium graveolens L. Carum carvi L. Chamomilla recutita (L.) Rausch. Coriandrum sativum L. Foeniculum vulgare Mill. Geranium macrorrhisum L.

Hyssopus officinalis L. Melissa officinalis L. Origanum vulgare L. ssp. vulgare Origanum vulgare L. ssp. hirtum (Link.) Jetswaart. Salvia officinalis L. Salvia sclarea L. Satureja montana L. Thymus serpillum L.

Appendix 8. Species of Food Plants

Castanea sativa Mill. Chenopodium bonus henricus L. Cornus mas L. Corylus avellana L. Daucus carota L. Fragaria vesca L. Heracleum sibiricum L. Humulus lupulus L. Mentha spicata L. ssp. spicata Mespilus germanica L. Prunus spinosa L. Pyrus communis L. Raphanus raphanistrum L.

Ribes nigrum L. Rosa canina L. Rubus caesius L. Rubus idaeus L. Rumex acetosa L. Sinapis arvensis L. Sorbus aria Crantz. Sorbus aucuparia L. Sorbus domestica L. Urtica dioica L. Vaccinium myrtillus L. Vaccinium vitis-idaea L.

Appendix 9. Species of Melliferous Plants

Acer campestre L. Aesculus hyppocastanum L. Althaea officinalis L. Anchusa officinalis L. Anethum graveolens L. Angelica sylvestris L. Anthylis vulneraria L. Arctium lappa L. Berberis vulgaris L. Berteroa incana (L.) DC. Brassica nigra (L.) Koch. Cannabis sativa L. Capsella bursa-pastoris (L.) Medic. Carduus acanthoides L. Carduus nutans L. Carlina acanthifolia All. Cercis siliquastrum L. Cichorium intybus L. Cirsium arvense (L.) Scop. Clematis vitalba L. Clinopodium vulgare L. Crataegus monogyna Jacq. Daucus carota L. Dipsacus laciniatus L. Echium vulgare L. Foeniculum vulgare Mill. Salvia officinalis L. Salvia sclarea L. Sambucus ebulus L. Sambucus nigra L. Satureja montana L. Sorbus aucuparia L. Sorbus domestica L. Stellaria media L. Syringa vulgaris L. Teucrium chamaedrys L. Tilia cordata Mill. Tilia platyphyllos Scop. Tilia tomentosa Moench. Trifolium alpestre L.

Genista tinctoria L. Geranium macrorrhisum L. Hedera helix L. Lamium purpureum L. Lathyrus pratensis L. Lathyrus tuberosus L. Leonurus cardiaca L. Ligustrum vulgare L. Lotus corniculatus L. Melilotus officinalis (L.) Pall. Melilotus albus Med. Melissa officinalis L. Mentha spicata L. ssp. spicata Mespilus germanica L. Nepeta cataria L. Ononis spinosa L. Ononis arvensis L. Onopordon acanthium L. Origanum vulgare L. ssp. vulgare Paeonia peregrina Mill. Paliurus spina-christi Mill. Papaver rhoeas L. Raphanus raphanistrum L. Rubus caesius L. Rubus idaeus L. Salvia pratensis L. Trifolium hybridum L. Trifolium patens Schreb. Trifolium repens L. Ulmus glabra Huds. Ulmus laevis Pall. Ulmus minor Mill. Viburnum lantana L. Viburnum opulus L. Vicia cracca L. Vinca minor L. Viola odorata L. Viola tricolor L. Viscum album L.

Appendix 10. Species of Medicinal Plants

Achillea millefolium L. Achillea clypeolata S. et S. Acorus calamus L. Adonis vernalis L. Aesculus hippocastanum L. Agrimonia eupatoria L. Allium ursinum L. Alnus glutinosa Gaertn. Althaea officinalis L. Anagalis arvensis L. Anchusa officinalis L. Anethum graveolens L. Angelica sylvestris L. Apium graveolens L. Arctium lappa L. Arctostaphylos uva-ursi (L.) Spreng. Aristolochia clematitis L. Artemisia absinthium L. Artemisia santonicum L. Artemisia alba Turra. Arum maculatum L. Asarum europeum L. Asplenium trichomanes L. Astragalus glycyphyllos L. Atropa belladonna L. Berberis vulgaris L. Betonica officinalis L. Betula pendula Roth. Bistorta major Gray. Brassica nigra (L.) Koch. Bryionia alba L. Cannabis sativa L. Capsella bursa-pastoris (L.) Med. Carduus acanthoides L. Carlina acanthifolia All. Carum carvi L. Castanea sativa Mill. Centaurium erythraea Rafn. Centaurea cyanus L. Geranium macrorrhisum L. Geum urbanum L. Glaucium flavum Grantz. Glycyrrhiza glabra L. Gypsophila paniculata L. Hedera helix L. Helleborus odorus W. et K. Helichrysum arenarium (L.) Moench. Heracleum sibiricum L. Herniaria glabra L. Herniaria hirsuta L. Hieracium pilosella L. Humulus lupulus L. Hypericum perforatum L. Hyssopus officinalis L. Inula helenium L. Juniperus communis L. Juniperus oxycedrus L. Leonurus cardiaca L. Leucojum aestivum L. Linaria vulgaris Mill. Lithospermum officinale L. Malva sylvestris L. Marrubium vulgare L. Melilotus officinalis (L.) Pall. Melissa officinalis L. Mentha pulegium L. Menyanthes trifoliata L. Nasturcium officinalis Br. Ononis spinosa L. Ononis arvensis L. Onopordon acanthium L. Orchis maculata L. Origanum vulgare L. ssp. vulgare Origanum vulgare L. ssp. hirtum (Link.) Jetswaart. Paeonia peregrina Mill. Paliurus spina-christi Mill. Papaver rhoeas L. Petasites hybridus (L.) Gaertn. Persicaria hydropiper (L.) Epach. Peucedanum officinale L. Phyllitis scolopendrium (L.) Newm. Physalis alkekengi L. Pimpinella saxifraga L. Pinus sylvestris L. Plantago lanceolata L. Plantago major L. Polygonum aviculare L. Polypodium vulgare L. Potentilla erecta (L.) Rausch. Potentilla reptans L. Primula veris L. Prunus spinosa L. Pulmonaria officinalis L.

Chamomilla recututa (L.) Rausch. Chelidonium majus L. Chenopodium bonus henricus L. Cichorium intybus L. Clematis vitalba L. Clinopodium vulgare L. Cnicus benedictus L. Colchicum automnale L. Consolida regalis Gray. Convallaria majalis L. Coriandrum sativum L. Cornus mas L. Corylus avellana L. Cotinus coggygria Scop. Crataegus monogyna Jacq. Cynodon dactylon (L.) Pers. Datura stramonium L. Dictamnus albus L. Digitalis lanata Ehrh. Dryopteris filix-mas (L.) Schott. Ecbalium elaterium (L.) A.Rieh. Elymus repens (L.) Gould. Equisetum arvense L. Eryngium campestre L. Euphrasia officinalis L. Filipendula vulgaris Moench. Foeniculum vulgare Mill. Fragaria vesca L. Frangula alnus Mill. Fraxinus excelsior L. Fraxinus ornus L. Fumaria officinalis L. Galega officinalis L. Galium aparine L. Galium odoratum (L.) Scop. Galium verum L. Genista tinctoria L. Gentiana asclepiadea L. Gentiana cruciata L. Geranium sanguineum L. Quercus cerris L. Quercus pedunculiflora C. Koch. Quercus robur L. Rhamnus cathartica L. Rhodiola rosea L. Ribes nigrum L. Rosa canina L. Rubia tinctorum L. Rubus caesius L. Rubus idaeus L. Rumex alpinus L. Ruscus aculeatus L. Ruta graveolens L. Salix alba L. Salix purpurea L. Salvia officinalis L. Sambucus ebulus L. Sambucus nigra L. Saponaria officinalis L. Satureja montana L. Sedum acre L. Sideritis scardica Grsb. Silybum marianum (L.) Gaertn. Sinapis arvensis L. Solanum dulcamara L. Solidago virga-aurea L. Sorbus aucuparia L. Sorbus domestica L. Stellaria media L. Symphytum officinale L. Syringa vulgaris L. Tamus communis L. Tanacetum vulgare L. Taraxacum officinale Web. Teucrium chamaedrys L. Teucrium polium L. Thalictrum minus L. Thymus serpillum L. Tilia cordata Mill. Tilia platyphyllos Scop. Tilia tomentosa Moench. Trigonella coerulea (L.) Ser. Tussilago farfara L. Urtica dioica L. Urtica urens L. Vaccinium myrtillus L. Vaccinium vitis-idea L. Valeriana officinalis L. Veratrum lobelianum Bernh. Verbascum nobile Vel. Verbascum phlomoides L. Verbascum thapsiforme Scrod. Verbena officinalis L. Veronica officinalis L. Vinca minor L. Viola odorata L. Viola tricolor L. Viscum album L.

Appendix 11. Species of Plants With Technical Uses

Abies alba Mill. Acer campestre L. Acer platanoides L. Alnus glutinosa Gaertn. Betula pendula Roth. Cannabis sativa L. Carpinus betulus L. Carpinus orientalis L. Chenopodium bonus henricus L. Cotinus coggygria Scop. Fagus orientalis Lipsky. Fagus sylvatica L. Fraxinus excelsior L. Fraxinus ornus L. Gypsophila paniculata L. Juniperus communis L. Juniperus oxycedrus L. Paliurus spina-christi Mill. Picea abies (L.) Karst. Pinus sylvestris L.

Pinus nigra Arm. Pinus peuce Grsb. Pinus mugo Turra Platanus orientalis L. Populus alba L. Populus canescens (Ait) Sm. Populus nigra L. Populus tremula L. Quercus cerris L. Quercus frainetto Tenore. Quercus pedunculiflora C. Koch. Quercus pubescens Willd. Quercus robur L. Salix alba L. Salix fragilis L. Salix purpurea L. Saponaria officinalis L. Ulmus glabra Huds. Ulmus laevis Pall. Ulmus minor Mill.

Appendix 12. Species of Forage Plants

Agropyrum cristatum (L.) Gaertn. Agrostis capillaris L. Agrostis canina L. Agrostis rupestris All. Alopecurus pratensis L. Alopecurus rendlei Eig. Alopecurus myosuroides Huds. Antoxantum odoratum L. Anthylis vulneraria L. Arrhenatherum elatius (L.) Beauv. ex J. et C. Presl. Avena fatua L. Berteroa incana (L.) DC. Briza media L. Bromus arvensis L. Bromus erectus Hugs. Bromus inermis Lyss. Bromus mollis L. Calamagrostis arundinaceae (L.) Roth. Calamagrostis epigeios (L.) Roth. Carex curvula All. Carex hirta L. Carex ovalis Good. Carex pallescens L. Chrysopogon grillus (L.) Trin. Coronilla varia L. Cynodon dactylon (L.) Pers. Cynosurus cristatus L. Cynosurus echinatus L. Dactylis glomerata L. Daucus carota L. Deschampsia caespitosa (L.) Beauv. Onobrychis arenaria (Kit.) DC. Phleum alpinum L. Phleum phleoides (L.) Karst. Phleum pratense L. Poa alpina L. Poa annua L. Poa bulbosa L. Poa palustris L. Poa pratensis L. Poa sylvicola Guss. Sesleria coerulea (L.) Ard. Sesleria comosa Vel. Trifolium alpestre L. Trifolium arvense L. Trifolium campestre Schreb. Trifolium hybridum L.

Elymus arenarius L. Elymus repens (L.) Gould. Festuca airoides Lam. Festuca fallax Thull. Festuca myurus L. Festuca paniculata (L.) Schinze et Thell. Festuca poaeformis Host. Festuca pratensis Huds. Festuca pseudovina Hack. et Wiesd. Festuca valida (Uechtr.) Penzez. Holcus lanatus L. Holcus mollis L. Hordeum bulbosum L. Lathyrus aphaca L. Lathyrus hirsutus L. Lathyrus nissolia L. Lathyrus pratensis L. Lathyrus sylvestris L. Lathyrus tuberosus L. Lolium perenne L. Lolium multiflorum Lam. Lotus corniculatus L. Luzula campestris (L.) DC. Medicago arabica (L.) Hugs. Medicago falcata L. Medicago lupulina L. Melica ciliata L. Melilotus officinalis (L.) Pall. Melilotus albus Med. Nardus stricta L. Onobrychis alba (W. et K.) Desv. Onobrychis vacifolia Scop. Trifolium incarnatum L. Trifolium montanum L. Trifolium patens Schreb. Trifolium pratense L. Trifolium repens L. Urtica dioica L. Vicia angustifolia Grufb. Vicia bithynica L. Vicia cracca L. Vicia grandiflora Scop. Vicia hirsuta (L.) S.F.Gray. Vicia tenuifolia Roth. Vicia tetrasperma (L.) Schreb. Vicia varia Host. Vicia villosa Roth.

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Kitanov, B. and R. Drenkovski. 1975. "Uber die Taxonomie einiger Sippen der Gattung Crocus L. auf der Balkahalbinsel." Pp 212-215 in Proceedings of the First International Symp. on Balkan Flora and Vegetation. Sofia: Publ. House of Bulgarian Academy of Science.

Kitanov, B. and I. Penev. 1980. Flora of Dobrudja. Sofia: Nauka i izkustvo.

Kitanov, B. and G. Kitanov. 1990. Flora of Pirin. Sofia: Nauka i izkustvo.

Kocev, C. 1968. "Centaurea kamciensis - a new centaurea species from the eastern Balkan Mountain Region." Comptes rendus de l'Academie Bulgare des Sciences 2: 151-153.

Koeva-Todorovska, J. 1988. "State and preservation of rare and protected plant species along the Bulgarian Black Sea coast." Annuaire de l'Universite de Sofia. 79,2: 110-113.

Kolev, I. 1963. The Weeds in Bulgaria. Sofia: Publ. House of the Bulgarian Academy of Science.

Kolev, I. and D. Terziiski. 1969. "A comparative taxonomic study of Vicia pannonica Crantz and V. striata M.B." Genetica, Moscow 5,1: 22-36.

Kovanda, M. and M. Anchev. 1989. "The Campanula rotundifolia complex in Bulgaria." Preslia (Praha) 61: 193-207.

Kozuharov, S. 1965. "The species of genus Medicago (Alfalfa) in Bulgaria." Abstract in English. Bulletin of the Botanical Institute. Bulgarian Academy of Sciences 15: 119-188.

Kozuharov, S. 1966. "The flora of Bulgaria." Gardeners Chronicle 160 (13):9; 14:23; 15:22.

Kozuharov, S. and B. Kuzmanov. 1967. A Key for Distinguishing the Weeds. Sofia: Zemizdat.

Kozuharov, S. and B. Kuzmanov. 1968. "Cytotaxonomic studies on Bulgarian Gramineae." Comptes rendus de l'Academie Bulgare des Sciences 3: 269-272.

Kozuharov, S. 1968. "Revision of the collection from the genus Jurinea Cass. in the Sofia herbaria." Bulletin of the Botanical Institute. Bulgarian Academy of Science. 18: 67-73.

Kozuharov, S. 1968. "Notes on the chorology to the Bulgarian Ferns (Pteridophyta)." Bulletin of the Botanical Institute. Bulgarian Academy of Science. 18: 111-119.

Kozuharov, S. and B. Kuzmanov. 1969. "Biosystematic studies on flowering plants in Bulgaria." Pp. 203-211 in Symposio Flora Europaea, 20-30 May 1967. Seville: Publ. Univ. Sevilla.

Kozuharov, S. and B. Kuzmanov. 1970. "On the taxonomic value and systematic position of some endemic Balkan Arenaria and Minuartia species." Fragmenta Floristica et Geobotanica (Krakov) 16,4: 449-452.

Kozuharov, S. and B. Kuzmanov. 1971. "A review of recent developments and future tasks in phytotaxonomy in Bulgaria." Journal of the Bulgarian Academy of Science. 2: 45-58.

Kozuharov, S., M. Stoeva, and B. Kuzmanov. 1974. "Taxonomic investigation of the annual species of the genus Bromus L. (Bromegrass) in Bulgaria." Bulletin of the Botancial Institute.

Kozuharov, S., A. Petrova, and M. Stoeva. 1974. "Cytotaxonomic study of Poaceae genus Briza." Comptes rendus de l'Academie Bulgare des Sciences 27,3: 383-385.

Kozuharov, S. 1975. "On endemism in the Bulgarian flora." Pp. 162-168 in D. Jordanov, ed., Problems of the Balkan Flora and Vegetation. Proceedings of the First Intern. Symp. Balkan Flora and Vegetation. Varna, June 1973. Sofia: Publishing House of the Bulgarian Academy of Science.

Kozuharov, S. 1977. "Centers of form differentiation and endemism in the Bulgarian flora: conservation and enrichment of the genetic fund." Problems of Biology 10: 34-61.

Kozuharov, S. and V. Najdenov. 1979. The Bioresources of Bulgaria. Sofia: Narodna Prosveta.

Kozuharov, S., A. Petrova, and F. Ehrendorfer. 1981. "Evolutionary patterns in some Brome grass species of the Balkan Peninsula." Botanische Jahrbucher fur Systematik (Stuttgart) 102,1-4: 381-391.

Kozuharov, S. and A. Petrova. 1981. "Karyological studies on Bulgarian Poaceae." Boletim sociadade Brotheriana ser. 2 (Coimbra, Portugalia) 53,2: 1161-1175.

Kozuharov, S. and A. Petrova. 1981. "The karyotype of a relict grass species and some notes on its relations." Boletim sociadade Brotheriana ser. 2 (Coimbra, Portugalia) 53(2): 1177-1181.

Kozuharov, S. 1981. "Protection of the herbaceous genefund in the forest belt of Bulgaria." Regional Symposium under Projekt 8, MAB. Blagoevgrad, 20-24 October 1980. S. Bulgarian Academy of Sciences, 239-249.

Kozuharov, S. 1982. "State of the investigations of the composition, distribution, and phytogeographic relationships in the genus Festuca (Fescue) in Bulgaria." Abstract in English. Annuaire de l'Universite de Sofia. 75,2: 11-20.

Kozuharov, S. and Z. Popova. 1983. "Contribution to specification of the composition of the genus Stipa L. in Bulgaria." Abstract in English. 90 Years Academician Daki Jordanov, Omurtag: 76-85.

Kozuharov, S., A. Petrova, and E. Janeva. 1983. "Cytotaxonomic studies of the genus Aegilops L. in Bulgaria." Abstract in English. Third National Conference of Botany, 26-30 October 1981, Sofia. Bulgarian Academy of Sciences, 207-214.

Kozuharov, S. and A. Petrova. 1991. "Chromosome numbers of Bulgarian angiosperms." Fitologija 39: 72-77.

Kuzmanov, B. 1963. "A taxonomic study of the species of the genus Euphorbia L. widespread in Bulgaria." Abstract in English. Bulletin of the Botanical Institute. Bulgarian Academy of Science 12: 101-186.

Kuzmanov, B. 1969. "Some aspects of the origin of the Bulgarian flora." Pp. 133-147 in Symposio Flora Europaea, 20-30 May 1967. Seville: Publ. Universidad de Sevilla.

Kuzmanov, B. and S. Kozuharov. 1971. "Aliens in the Bulgarian flora." Boissiera 19: 319-327.

327. Kuzmanov, B. and S. Simeonov. 1972. "Taxonomic studies of the Bulgarian species of the genus Tragopogon L." Abstract in English. Bulletin of the Botanical Institute. Bulgarian Academy of Science. 22: 5-32.

Kuzmanov, B. 1974. "Taxonomic studies of vascular plants in Bulgaria, 1961-1971." Boletim sociadade Brotheriana (Coimbra, Portugalia) 24,1: 25-79.

Kuzmanov, B. 1978. "Cytotaxonomic investigations of the Bulgarian leguminous plants." Abstract in English. Pp. 11-71 in S. Kozuharov and B. Kuzmanov, eds., Evolution of Flowering Plants and Florogenesis. 1. Fabaceae, Scrophulariaceae, Rubiaceae. Sofia: Publishing House of the Bulgarian Academy of Science.

Kuzmanov, B., N. Andreev, and V. Kozovska. 1980. "Chemotaxonomic study of Bulgarian species of Peucedanum L. I." Anales del Jardin botanico de Madrid (Madrid) 37-II: 779-788.

Kuzmanov, B. 1981. "Balkan endemism and the problem of species conservation, with particular reference to the Bulgarian flora." Botanische Jahrbucher fur systematik (Stuttgart) 102,1-4: 255-270.

Kuzmanov, B. 1981. "Mapping and protection of the threatened plants in the Bulgarian flora." Pp. 95-156 in V. Velcev and S. Kozuharov, eds., Mapping the Flora of the Balkan Peninsula. Sofia: Publishing House of the Bulgarian Academy of Science.

Kuzmanov, B., N. Thin, and S. Georgieva. 1981. "A cytotaxonomic study on Bulgarian Anthemis species." Candollea (Geneve) 36: 19-76.

Kuzmanov, B. and H. Dutschevska. 1982. "Chemosystematics of Thalictrum minus complex." Journ. Nat. Prod. (U.S.A.) 45,3: 295-310.

Kuzmanov, B. and P. Jurukova-Grancarova. 1983. "Evolutionary trends in the Bulgarian Compositae plants." Abstract in English. Fitologija 23: 3-29.

Kuzmanov, B. 1991. "Evolutionary trends of Bulgarian Compositae." Abstract in English. Pp. 7-84 in S. Kozuharov and B. Kuzmanov, eds., Evolution of Flowering Plants and Florogenesis. 2. Asteraceae, Brassicaceae, Poaceae, Cyperaceae. Sofia: Publishing House of the Bulgarian Academy of Science.

Marinov, M., S. Nedjalkov, and Z. Naumov. 1961. The Beech Forests in Bulgaria. Sofia: Zemizdat.

Markova, M. 1974-1975. "Kariosystematische, Untersuchungen an den Cistaceae, Bulgariens." Plant, Systematics, and Evolution (Wien) 123,4: 283-315.

Markova, M. and Z. Cherneva. 1984. "Karylogical studies on two species new to the Bulgarian flora." Abstract in English. Fitologija 27: 35-39.

Markova, M. 1985. "Karyotaxonomische Untersuchungen an Potentilla taurica s.l. in Bulgarien." Folia Geobot. Phytotax. (Praha) 20,2: 185-196.

Mitrev, A. and S. Popova. 1982. An Atlas of the Medical Plants in Bulgaria. Sofia: Publishing House of the Bulgarian Academy of Science.

Ninova, D., B. Kuzmanov, R. Ruseva, and M. Kurteva. 1984. "Morphological variability of Glechoma hirsuta Wald. et Kit. and G. hederaceae L." Abstract in English. Fitologija 26: 3-59.

Peev, D. 1970. "An investigation of the three primula species from the section Aleuritia Duby found in Bulgaria." Bulletin of the Botanical Institute. Bulgarian Academy of Science. 20: 131-150.

Peev, P. 1972. "New taxa and ploidy levels of some Bulgarian Veronica species." Comptes rendus de l'Academie Bulgare des Sciences 6: 811-814.

Peev, P. 1977. "Chromosome numbers and critical notes on the taxonomy of some Primulaceae species in Bulgaria." Abstract in English. Fitologija 7: 3-9.

Peev, D. 1978. "Taxonomy and microevolution of the wild-growing representatives of the genus Veronica L. in Bulgaria." Abstract in English. Pp. 72-106 in S. Kozuharov and B. Kuzmanov, eds., Evolution of Flowering Plants and Florogenesis. 1. Fabaceae, Scrophulariaceae, Rubiaceae. Sofia: Publishing House of the Bulgarian Academy of Science.

Peev, D. and S. Kozuharov. 1991. "Variability correlations and factor analysis of racemes of three annual species of the genus Bromus L. in Bulgaria." Abstract in English. Pp. 119-139 in S. Kozuharov and B. Kuzmanov, eds., Evolution of Flowering Plants and Florogenesis. 2. Asteraceae, Brassicaceae, Poaceae, Cyperaceae. Sofia: Publishing House of the Bulgarian Academy of Science.

Penev, I. and S. Kozuharov. 1968. "A new foxtail grass from Bulgaria." Notes from the Royal Botanic Garden 38,2: 187-188.

Petrova, A. and S. Kozuharov. 1982. "Cytotaxonomic study of genus Trifolium L. in Bulgaria." Abstract in English. I. Fitologija 19: 3-23; II. Fitologija 20: 20-41.

Petrova, A. and S. Kozuharov. 1983. "Cytotaxonomic studies of genus Agropyron Gaertn. in Bulgaria." Abstract in English. Third National Conference of Botany, 26-30 October 1981, Sofia. S. Bulgarian Academy of Science.: 215-222.

Petrova, A., S. Kozuharov, and T. Banchev. 1984. "Interrelation between the karyological particularities and distribution of the species of genus Hordeum s.l. in Bulgaria." Contemporary theoretical and applied aspects of plant ecology. S. Bulgarian Academy of Science. 1: 234-243.

Popova, M. 1970. "Some remarks on the lilies of the Balkans." The Lily Year Book. Royal Horticultural Society (London): 151-153.

Popova, M. 1983. "Rosa smoljanensis Popova ssp. nova (Sect. Caninae Crep.)." Abstract in English. Third National Conference of Botany, 26-30 October 1981, Sofia. S. Bulgarian Academy of Science.: 173-174.

Stanev, S. 1970. "On the history of the Bulgarian relict endemics. I. Astragalus physocalix Frisch." Abstract in English. Bulletin of the Nat. Science Museum (Plovdiv) 1: 31-36.

Stanev, S. 1973. "On the history of the Bulgarian relict endemics. II. Haberlea rhodopensis Friv." Abstract in English. Bulletin of the Nat. Science Museum (Plovdiv) 2: 31-42.

Stanev, S. 1973. "Floristic materials from the eastern Sredna Gora Mountains with critical notes. I." Abstract in English. Bulletin of the Botanical Institute Bulgarian Academy of Science. 23: 219-228.

Stanev, S. 1975. "Floristic materials from the Besaparski ridges with critical notes. II." Abstract in English. Fitologija 1: 82-87.

Stanev, S. 1975. "Floristic materials from the Bulgarian flora with critical notes." Abstract in English. In Honour of Academician Daki Jordanov. Sofia: Publ. House Bulgarian Academy of Science., 253-263.

Stanev, S. 1979. "Materials and critical notes on the Bulgarian flora." Abstract in English. Fitologija 13: 71-75.

Stefanoff, B. 1921. "Fur die Flora Bulgariens neue und seltene Pflanzen." Osterreichische Botanische Zeitschrift 70,3-5: 11-114.

Stefanoff, B. 1926. "Colchicum davidovii n. sp." Bulletin of the Bulgarian Botanical Society 1: 69-70.

Stefanoff, B. 1926. "Monograph of the genus Colchicum L." Proceedings of the Bulgarian Academy of Science. 22: 101.

Stefanoff, B. 1929. "Funf neue Arten aus Bulgarien und Thrakien." Bulletin of the Bulgarian Botanical Society. 3: 77-85.

Stefanoff, B. 1930. "Poa Borisii nov. spec." Mitteil. Konigl. Naturwiss. Inst. Sofia 3: 138-140.

Stefanoff, B. 1930. "Poa Borisii nov. spec." Mitteil. Konigl. Naturwiss. Inst. Sofia 3: 138-140.

Stefanoff, B. and D. Jordanov. 1931. "Topographische Flora von Bulgarien." Botanische Jahrb. 64,4-5: 388-536.

Stefanoff, B. 1931. "Notes supplementaires pour l'etude des chenes roburoides de Strandzha Planina (Bulgarie du sud-est)." Bulletin des Instituts Royales D'Histoire Naturale. Sofia 4: 65-77.

Stefanoff, B. 1931. "Notes on new or rare Hyperica." Bulletin of Miscellaneous Information, Royal Botanic Gardens (Kew)1: 29-33.

Stefanoff, B. 1932. "Notes systematiques sur le Pin Leucoderme." Bulletin de la Societe dendrologique de France (Paris) 81: 8-15.

Stefanoff, B. 1934. "Neue Materialen zur Kenntnis der Flora von Bulgarien." Magyar Bot. Lapok (Budapest) 33,1-12: 1-15.

Stefanoff, B. 1936. "Remarks upon the causes determining the relict distribution of plants." Journal of the Bulgarian Academy of Science. (Sofia) 53: 178.

Stefanoff, B. 1936. "On the systematic position of some species from Campanulaceae family." Annuaire de l'Universite de Sofia 14,2: 93-104.

Stefanoff, B. and T. Georgiev. 1937. "Ramondia serbica Panc. in Bulgaria." Annuaire de l'Universite de Sofia 15,2: 42-53.

Stefanoff, B. 1943. Phytogeographycal Elements in Bulgaria. Sofia: Print. House "Knipegraf."

Stefanoff, B. 1947. "Sedum stefco nov. spec. und S. erythreum Grsb." Annuaire de l'Universite de Sofia 25,2: 105-112.

Stefanoff, B. 1954. A Guide to the Local and Some Foreign Tree Species and Shrubs in Summer and Winter Condition and According the Wood of the Cortex. Sofia: Zemizdat.

Stefanoff, B. and S. Nedjalkov. 1956. "Quercus thracica nov. spec. - Arbor Memorabilis." Bulletin of the Botanical Institute Bulgarian Academy of Science. 5: 39-53.

Stefanoff, B. and B. Kitanov. 1962. Cultigene Plants and Cultigene Vegetation in Bulgaria. Abstract in German. Sofia: Bulgarian Academy of Science.

Stefanoff, B. 1963. "Naturliche Populationen einiger Iris pumila - Formen mit mannigfalting gefarbten Bluten." Atti del 1 Simposio Internat. dell'Iris. Firenze: 245-251.

Stefanoff, B. and B. Kitanov. 1963. "On the ecological evolution of the Thracian-bysantian relict endemic flora." Abstract in German. Bulletin of the Institute of Forestry. 12: 5-59.

Stefanoff, B. 1973. "Neueres zur Herkunft und Taxonomie der Quercus thraceca Stef. et Ned." Acta Botan. Acad. Scient. Hung. 19,1-4: 343-357.

Stefanoff, B. and M. Bankov. 1978. "Floristic communication for certain plants with rare places of provenance in Bulgaria." Abstract in English. Forest Science (Sofia) 15,5: 96-97.

Stefanoff, B. and M. Bankov. 1978. "Concerning the very rare or recently extinct species from the Bulgarian flora and the causes behind the restriction of their habitat." Abstract in English. Forest Science (Sofia) 15,6: 3-10.

Stojanoff, N. and B. Stefanoff. 1921. "Zwei neue Pflanzen aus Bulgarien." Osterreichische Botanische Zeitschrift 70,3-5: 103-107.

Stojanoff, N. 1924. "Das Vorkommen von Malcolmia angulifolia Boiss. et Spr. in Bulgarisch-Mazedonien." Osterreichische Botanische Zeitschrift 1-3: 61-62.

Stojanoff, N. and B. Stefanoff. 1921. A List of the Plants Found in Bulgaria. Sofia: House "Artist."

Stojanoff, N. and B. Stefanoff. 1921. "The grasses of Bulgaria." Abstract in German. Archive of the Ministry of Agriculture and State Properties 2: 1-96.

Stojanoff, N. and B. Stefanoff. 1922. "Phytogeographycal and floristic characteristics of the Pirin Mountains." Annuaire de l'Universite de Sofia 18: 1-27.

Stojanoff, N. and B. Stefanoff. 1923. Flora of Bulgaria. Vol. I. Sofia: Public Print. House.

Stojanoff, N. and B. Stefanoff. 1923. "A new Veronica from Bulgaria." Journal of Botany. 61: 219-220.

Stojanoff, N. and B. Stefanoff. 1923. "Beitrag zur Flora Bulgariens und Mazedoniensis." Osterreichische Botanische Zeitschrift 1-5: 85-92.

Stojanoff, N. and B. Stefanoff. 1924. "Verbascum pseudonobile sp. n." Annuaire de l'Universite de Sofia 2: 71-73.

Stojanoff, N. and B. Stefanoff. 1924. "Ein neuer Beitrag zur Flora Bulgariens." Osterreichische Botanische Zeitschrift 10-12: 281-283.

Stojanoff, N. and B. Stefanoff. 1924. "Scabiosa rhodopensis." Bulletin of Miscellaneous Information, Royal Botanic Gardens (Kew) 3: 98-99.

Stojanoff, N. and B. Stefanoff. 1925. Flora of Bulgaria. Vol. II. Sofia: Public Print. House.

Stojanoff, N. and B. Stefanoff. 1925. "Eine neue Chondrilla aus Bulgarien." Botanische Jahrb. 59,5: 16.

Stojanoff, N. 1926. "Uber den Formenkreis von Jasione supina (Sieb.) DC." Notizblatt des Bot. Gart. u. Mus. Berlin-Dahlem 89,7: 545-560.

Stojanoff, N. 1926. "Beitrage zur Flora Bulgariens und der angrenzenden Lander." Bulletin of the Bulgarian Botanical Society 1: 71-82.

Stojanoff, N. 1928. "Uber die Bulgarien vorkommenden Formen von Verbascum humile Janka." Mitteil. Konigl. Naturwiss. Inst. Sofia 1: 142-144.

Stojanoff, N. 1929. "Kritische Studien und kleine Mitteilungen aus dem Herbar Koniglichen Naturhistorischen Museums in Sofia. I." Mitteil. Konigl. Naturwiss. Inst. Sofia 2: 257-272.

Stojanoff, N. 1929. "Der Longos-Wald in Bulgarien." Botanische Jahrbucher fur systematics (Leipzig) 62, 5: 502-523.

Stojanoff, N. 1930. "Kritische Studien und kleine Mitteilungen aus dem Herbar des Koniglichen Naturhistorischen Museums in Sofia. II." Mitteil. Konigl. Naturwiss. Inst. Sofia 3: 119-137.

Stojanoff, N. 1930. "Potentilla Regis-Borisii sp. n. e. sect. Rupestres eine neue Pflanzenart aus Bulgarien." Mitteil. Konigl. Naturwiss. Inst. Sofia 3: 249-252.

Stojanoff, N. 1930. "Versuch einer Analyse des relikten Elements in der Flora der Balkanhalbinsel." Botanische Jahrbucher fur systematik (Leipzig) 68,5: 368-418.

Stojanoff, N. 1932. "A new Europaean species of Fritillaria." The Lily Year Book. Royal Horticultural Society (London): 94-95.

Stojanoff, N. 1931. "Kritische Studien und kleine Mitteilungen aus dem Herbar des Koniglichen Naturhistorischen Museums in Sofia. III." Mitteil. Konigl. Naturwiss. Inst. Sofia 4: 139-156.

Stojanoff, N. and B. Stefanoff. 1933. Flora of Bulgaria. 2nd ed. Sofia: Cooper. Print. House.

Stojanoff, N. 1933. "Kritische Studien und kleine Mitteilungen aus dem Herbar des Koniglichen Naturhistorischen Museums in Sofia. IV." Mitteil. Konigl. Naturwiss. Inst. Sofia 6: 208-218.

Stojanoff, N. and B. Stefanoff. 1934. "Sedum tuberiferum Stoj. et Stef. sp. nova aus Bulgarien." Notizblatt des Bot. Gart. u. Mus. Berli-Dahlem 11,110: 1013-1023.

Stojanoff, N. and B. Achtaroff. 1934. "Uber den Begriff und die systematische Stellung von Centaurea affinis Friv. und Centaurea pallida Friv." Mitteil. Konigl. Naturwiss. Inst. Sofia 7: 91-105.

Stojanoff, N. 1934. "The dying out plants." Abstract in English. Miscellanea of the Union for Protection of the Nature 1: 34-38.

Stojanoff, N. and B. Achtaroff. 1935. Studien uber die Centaureen Bulgariens. Herausg. Bulg. Akad. Wissenschaften aus der Stift. Ivan and Janko K. Urumoff, Sofia: 5-84.

Stojanoff, N. and B. Achtaroff. 1935. "Kritische Studien uber die Nelken Bulgariens." Proceedings of the Bulgarian Academy of Science. 29: 3-101.

Stojanoff, N. and B. Achtaroff. 1937. "Material zur Kenntnis der Gattung Anthemis (verlaufige Mitteilung)." Notizblatt des Bot. Gart. u. Mus. Berlin-Dahlem 13,119: 513-523.

Stojanoff, N. 1941. "Kritische Studien und kleine Mitteilungen aus dem Herbar des Koniglichen Naturhistorischen Museums in Sofia. VI." Mitteil. Konigl. Naturwiss. Inst. Sofia 14: 153-167.

Stojanoff, N. and B. Achtaroff. 1941. "Uber einige neue interessante Arten der Gattung Anthemis." Journal of the Bulgarian Academy of Science. (Sofia) 61,32: 73-86.

Stojanoff, N. and B. Achtaroff. 1942. "Uber die Centaureen Bulgariens." Journal of the Bulgarian Academy of Science. (Sofia) 65,32: 169-189.

Stojanoff, N. and B. Stefanoff. 1948. Flora of Bulgaria. 3rd ed. Sofia: Print House of the University.

Stojanoff, N. and B. Kitanov. 1960. Useful Wild Plants in Bulgaria. Sofia: Publ. House of the Bulgarian Academy of Science.

Stojanoff, N. and B. Kitanov. 1966. Alpine Plants in Bulgaria. Sofia: Nauka i izkustvo.

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Stoeva, M. 1983. "Variation in the chromosome number in the bulbiferose Poa bulbosa L." Abstract in English. 90 years of Academician Daki Jordanov, Omurtag: 86-98.

Stoeva, M. and S. Kozuharov. 1983. "Two new species for section Bolboforum Aschers. et Graebn. of genus Poa L." Abstract in English. 90 years of Academician Daki Jordanov, Omurtag: 152- 157.

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Velenovsky, J. 1891. Flora Bulgarica. Descriptio et enumeratio systematica plantarum vascularium in principatu Bulgariae sponte nascentium. Pragae: Prostat apud Fr. Rivnac, Bipliopolam.

Velenovsky, J. 1898. Flora Bulgarica. Descriptio et enumeratio systematica plantarum vascularium in principatu Bulgariae sponte nascentium. Supplementum I. Pragae: Prostat apud Fr. Rivnac, Bipliopolam.

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