Delineation of Pannonicum

The speciality and unique character of the flora of the Great Hungarian Plain was already recognised by Kerner (1863). According to him, these grasslands are related to the steppes of the east (South Russia) and this is their “western island”. He also recognised that the steppe flora in the west along the Danube extends beyond Vienna to Wachau and the Moravian Basin. He had already used the term “Pannonian flora”, but still considered it the territory of the Pontic area (Kerner 1886). Borbás noticed the flora connection and similarity between the Hungarian Mountains and the Great Plain, and in his interpretation these together make up the Hungarian flora region (Borbás 1896, 1900). By the turn of the century, the first flora maps were completed (Borbás 1900, Kerner and Wettstein 1888). However, there was no agreement regarding the classification of the South Transdanubian flora. Kerner (1886) classified this as the Pannonian, while Borbás (1900) classified it as the Illyrian flora. At the beginning of the 20th century, many famous Hungarian botanists worked on the preparation of the flora classification in the Carpathian Basin (e.g. Borbás 1905, Jávorka 1924–1925, Rapaics 1910, Simonkai 1910, Soó 1933 a, Tuzson 1915), and researched the unique characters of the Pannonian flora and presented the differences from the Pontic flora (Borbás 1905, Rapaics 1918, Tuzson 1913, 1915). Rapaics (1910) roughly draws the boundaries of Pannonicum. The map of Jávorka’s book (1924–1925) essentially outlines the phytogeographical division of the Carpathian Basin accepted today. Soó (1933 b) synthesised the knowledge of that time and drew the boundaries of smaller phytogeographical units within the territory of historical Hungary. In his later work, he also outlines the boundaries of the Pannonian flora beyond the Carpathian Basin (Soó 1947) and draws up a comprehensive and detailed demarcation of the Pannonicum (floristic region), which (except for the north-western part) has remained essentially or only slightly changed.

In the second half of the 20th century, researchers examined the borders of the Pannonian flora and its smaller units only within the borders of their own country (e.g. Soó 1961). The western, northwestern, and northern parts of the Pannonicum’s border are the best researched and accepted. In the present dissertation, the works of Futák (1984), Király (2001), Michalko et al. (1986), Niklfeld (1964), Pócs (1981), Simon (2005), Skalický (1988), Vojtkó (2016), Will-ner (2013) are considered as guidelines for the delimitation in this section.

However, there are also two areas here where the flora boundary is not clear: Zemplén Mts in the northeast and the “Thermenlinie” in the west. In the case of the Zemplén Mts, it has long been a question of how far the Carpaticum extends into the Pannonicum. According to most authors, it extends deep into the south but Michalko et al. (1986) draw the line further north. Recent and more detailed research also supports this (Vojtkó in litt.). (The two types of delimination are shown by a dashed line on the map). The “Thermenlinie” is the area between the Vienna Basin and the Eastern Alps (south of Vienna). This very eastern margin of the Alps is strongly influenced by the Pannonian climate and phytogeographically it is a transitional area between the Alpicum and Pannonicum floristic regions with strong Pannonian influence (Willner 2013). Recent studies suggest that this Thermenlinie is part of the Pannonian region even though it belongs geologically to the Alps. However, it is a difficult question how many kilometres the Pannonian region penetrates into the Alps (Willner in litt.).

The southwestern border from the southern part of Burgenland (south of the rivers Pinka and Lafnitz) through Slovenia and Croatia to Bosnia and Serbia remains also questionable (Fekete et al. 2016, Marinček 1995, Niklfeld 1993, Willner 2013, Wraber 1969). In Slovenia, Wraber (1969) considered the eastern part of the country, east of the Maribor–Krško (Sava) and Kostanjevica (Krka) lines, to be a “sub-Pannonian” area, but mentioned that the most significant Pannonian influence in vegetation is only up to the Mura River. From here, to the west and south, the alpine influence is becoming more and more prevalent. Zupančič et al. (1987) classify areas south of the Slovenska Bistrica– Drava line as Illyricum floristic region.

The northern border of the Illyricum is mostly drawn at the foothills surrounding the Dinaric Mountains (Fukarek 1979, Meusel et al. 1965) or along the Sava river (from Zagreb) (Marinček 1995). South Slavic botanists consider the area between the Sava and the Drava river, and even to Lake Balaton to be transitional (“prepannonic region”) and classify it as Pannonicum, but mention that the Illyrian flora islands are still present here extrazonally (Marinček 1995). Fekete et al. (2016) (Hungarian botanists) do not accept this view, as they do not see what kind of floristic or vegetation arguments support such an extension of the boundary from the Pannonian side. The area between the Drava and the Sava is believed to be uncharacteristic and transitional, difficult or impossible to classify into any phytogeographical region. The areas north of the Drava river are named in Hungarian literature as “Praeillyricum” and are mostly classified as part of the Pannonicum (e.g. Pócs 1981).

The phytogeographical division of the area between the Sava and Lake Balaton is therefore not uniform, but the authors agree that it is a transitional region between Pannonicum and Illyricum. The delimitation of the Pannonicum was also based on the work of Soó (1947) in this section, but referring to the transitional area, the “boundary” on the map is indicated by a dashed line. The drawing of the eastern and southeastern borders with minor modifications (by the author) also follows the work of Soó (1947). (Fig. 1).

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Map showing the delineation of the Pannonicum and its subunits. T = Thermenlinie, X = Pannonian flora islands

Citation: Acta Botanica Hungarica 65, 1-2; 10.1556/034.65.2023.1-2.8

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Pannonicum is surrounded by the Carpaticum (north and east), Moesiacum (southeast), Illyricum (south), Alpicum (west) and Hercynicum (northwest) floristic regions.

Most of the area of the Pannonicum is located in Hungary, but the area is also located in Austria (part of Burgenland, the northeastern part of Lower Austria with the Hainburger Berge, which is geographically part of the Carpathians), the Czech Republic (southeastern Moravia, part of it belongs geographically to the Carpathians: Central and South Moravian Carpathians), the southern part of Slovakia, the western edge of Ukraine, the northwestern and western verge of Romania (Partium, Bánság), the northern part of Serbia, the northeastern edge of Bosnia, northeastern plains in Croatia and the northeastern edge of Slovenia.

Islands of the Pannonian flora

It is not part of the Pannonicum delineated here but there are some “Pannonian flora islands” along the lower part of the Danube outside the Carpathian Mountains. These are Pannonic sand steppes (Natura 2000 code: 6260), where endemic Pannonian species also occur (Vladimirov and Tsoneva 2006, Šefferová Stanová et al. 2008).

The Pannonian sand steppe vegetation can still be found on the northern edge of the Iron Gate in the wide valley around Golumbac (this work classifies this area as part of Pannonicum). After crossing the Carpathians (this gorge called Iron Gate) the Danube arrives in a flat area where it has deposited sandy alluvium in a few places. On these sand dunes appeared sand steppe vegetation with many Pannonian elements for example around Kladovo and Prahovo-Radujevac in Serbia. In the middle of the 19th century the area of these sand steppes reached 800 hectares in both places (Pančić 1863), but this decreased significantly by the end of the century (Adamović 1904). Since then most of them have been cultivated or degraded and only very small fragments have survived. Some of the previously found Pannonian species have become extinct: Colchicum arenarium, Iris arenaria, Sedum urvillei subsp. hillebrandtii. Others can still be found: Dianthus diutinus, D. pontederae, Tragopogon floccosus. A similar sand flora is found on the Romanian side of the Danube near Pisculet (occurrence of Colchicum arenarium and Festuca vaginata) and Gruia. Moreover, this Pannonian inland dunes type vegetation descends even to the northwestern edge of Bulgaria (Archar, Orsoya-Slivata) with Pannonian species, such as Festuca vaginata or Tragopogon floccosus (Vladimirov and Tsoneva 2006).

Division of Pannonicum

Pannonicum was divided into five parts by phytogeography (Molnár et al. 2018, Pócs 1981, Soó 1961, 1964 a): Eupannonicum, Matricum, Bakonyicum, Praeillyricum, Praenoricum.

Eupannonicum: The plains from Southern Moravia (Czech Republic) in the northwest to Deliblato Sands (Serbia) in the southeast. This area makes up nearly 75% of the Pannonicum. The Transdanubian and the North Hungarian Mountains divide into two parts. Within this delimited area there are some foothills, hills (e.g. Hainburger Berge, Kaszonyi-hegy) and mountain (Fruška Gora). Most of the area belongs to the forest-steppe zone.

Matricum: This is a mountain range (more or less the geographical North Hungarian Mountains – Északi-középhegység) from the Börzsöny to the southern part of the Zemplén Mts. Limestone (Bükk, Gömör-Tornai karszt/Gemersko-Turniansky Kras) and eruptive bedrocks (e.g. andesite, basalt) make up a significant part of the mountains. The vegetation is characterised by two faces. The flora of the higher altitudes (800–900 m), the northern exposed slopes and the gorge valleys are mountainous (include some Carpathian elements), while the lower areas and the southern slopes are mostly dominated by thermophilous Pannonian vegetation.

Bakonyicum: The Transdanubian Mountains (Dunántúli-középhegység) from the Danube Bend to the Keszthelyi-hegység. The most typical bedrock is dolomite and limestone here. The climate of this region has a strong sub-Mediterranean influence on the southern slopes.

Praeillyricum: This area has two mountains (Mecsek, Villányi-hegység) and collin regions (Somogy–Tolnai-dombvidék). It is an intermediate area between the Pannonicum and the Illyricum. The number of Illyrian elements is relatively high in the south but gradually disappears in the north.

Praenoricum: This is an intermediate zone between the Alpicum and the Pannonicum floristic regions.

Pannonian endemics in previous literature

The compilation of endemic species of an area or landscape within the Carpathian Basin was dealt with as early as the end of the 19th century (e.g. Borbás 1879, 1884, 1900, Grisebach 1872, Simonkai 1886). Some of the plants mentioned here are now considered synonyms, or non-endemic as they are more widespread. However, several of them are still considered endemic today: Centaurea scabiosa subsp. sadleriana, Cirsium brachycephalum, Dianthus diutinus, D. pontederae, Ferula sadleriana, Linum dolomiticum, L. hirsutum subsp. glabrescens, Seseli leucospermum, Noccaea (Thlaspi) jankae, etc. The first comprehensive and detailed compilation and analysis of the endemic vascular plants of the Carpathian Basin (Carpaticum and Pannonicum) can be attributed to Soó (1933 b).

The most detailed compilation of the endemism of the Pannonian flora to date is the result of the work of Tatár (1939) (student of R. Soó). The list is based on a detailed processing of the distribution area of about 55 taxa based on herbarium and literature data. The dissertation does not include such “critical” groups as Sorbus, Rosa, Rubus, Hieracium, Tilia, Thymus, Mentha. The article does not mention but did not process for example the genus Taraxacum or Ranunculus auricomus agg. group. The detailed processing of the distribution area of two other taxa considered to be endemic at that time (Ononis semi-hircina, Centaurium uliginosum) was carried out by U. Szabó (1939). Soó (1964 a) also publishes lists, but only of areas within the borders of Hungary.

Since then, only a few flora databases have collected the Pannonian endemics (e.g. Horváth et al. 1995, Simon et al. 1992). These include species described since 1939 (e.g. Scilla spetana, Vincetoxicum pannonicum), some subspecies (not all), some hybrids and several other taxa that are not considered endemic today. Fekete et al. (2011, 2014) also report compilations of Pannonian endemics. In the latter, they listed 36 species and subspecies and one hybrid, and it is mentioned that there are another 11 endemic apomictic Sorbus species. Futák collected the Pannonian endemics that live in Slovakia (Futák 1972).

Regarding Pannonian endemics, it should be mentioned that the phytogeographical Pannonicum and the geographical Carpathians overlap. The North Hungarian Mountains (phytogeographic: Matricum) for example are part of both, but also the Hainburger Berge (Austria) and a part of the Central and South-Moravian Carpathians (the Czech Republic). Therefore, there may be Carpathian endemics (in a geographical sense) (Kliment et al. 2016) that can also be treated as Pannonian endemics (in a floristic sense).

Delimitation of endemic and subendemic taxa and evaluation of endemism

Endemic taxa are those whose distribution is restricted to a particular geographic region or habitat (Bruchmann 2011, Hobohm 2014). The delimitation of the Pannonicum is not as clear as a national border or an island (see above). The boundary is not sharp on a fine scale. For example on the border of Pannonicum and Carpaticum, the southern warm slopes grow Pannonian vegetation while the northern exposed slopes and the gorge valleys have mountainous vegetation with many Carpathian elements and they are very close together. So these different flora patches often occur alternately in the area.

The delimitation of the phytogeographic units within the Pannonicum is not easy either. The Danube Bend area which is called Visegradense in the phytogeography is a transitional area between the Matricum (North Hungarian Mountains) and the Bakonyicum (Transdanubian Mountains). Endemic plants can be found here from both regions. There are some differences between the geographical and the phytogeographical regions as well. The sand steppe vegetation of the lowlands for example creeps up the foothills in several places. This is geographically a mountain region but phytogeographically vegetation of the lowlands.

Drawing sharp boundaries is therefore difficult, often impossible. In addition, there may be isolated occurrences in special habitats (e.g. on limestone hills or in sandy areas). In this paper, the geographical delimitation does not exclude endemic taxa restricted to a particular isolated occurrence of special habitats or habitat islands (e.g. to isolated outcrops of different types of bedrock, sand, etc.) (see Kliment et al. 2016).

As subendemic I considered taxa almost exclusively found only in a certain region, but with a limited occurrence also outside this region. Achillea asplenifolia, for example, is quite widespread in the Pannonicum, but can also be found in some places in the adjacent area. The distribution area of the Chamaecytisus heuffelii is limited to a few localities only. Most of the population lives in Pannonicum, but a significant number also live in the neighbouring Iron Gate Gorge. But taxa with very limited occurrence outside a given region, e.g. taxa with a single population close to the main distribution area or taxa occurring in a transition zone between two adjacent phytochorions, were evaluated as endemic to the given region (see Kliment et al. 2016). For example endemic to the Pannonicum with a single occurrence outside but not “far” from the border (e.g. Dianthus diutinus is an occurrence in a “Pannonian flora island” near Kladovo). On the other hand, taxa with frequent occurrence in neighbouring regions or with only a single occurrence but far from the Pannonicum (e.g. Rosa facsarii is an occurrence in Albania) were not considered to be endemic or subendemic. The phytogeographical status of “Thermenlinie” is not completely clear. Because of its transitional status, taxa that occur only here are considered Pannonian subendemic.

In the evaluation of endemism, only the natural range is taken into account for plant occurrence data. The Limonium gmelini agg. for example spreads along the Austrian and Czech roads outside the Pannonicum due to road salting and international traffic (Hohla et al. 2015, Kocián et al. 2016). These data were not taken into account when determining the distribution area of the Limonium. Taxa under the subspecies rank were not evaluated as endemic. Hybrids were not evaluated as endemic but stabilised hybridogenous taxa (e.g. the apomictic taxa) were considered endemic.

Apomictic taxa (Alchemilla, Hieracium, Pilosella, Rubus, Sorbus, Taraxacum, Ranunculus auricomus agg.) form a separate group. With understanding of the apomictic origin and evolutionary stability of intermediate (hybridogenous) taxa, in 20th century the majority of researchers accepted such taxa at the level of species, but isolated from sexually reproducing species they are often referred to as “microspecies” (Hörandl 2008, Kirschner and Štěpánek 1998, Sennikov and Kurtto 2017). Their evolutionary history is mostly young (post-glacial) and such species are still evolving recently.

Among these apomictic taxa, the genus Sorbus is represented by most known Pannonian endemic species. In the current understanding, the apomictic species of Sorbus s. l. are allopolyploid (triploid or tetraploid) with typically restricted areas, sometimes confined to a single locality in which they had possibly originated. They are either single clones or lineages descending from single clones, thus having a very narrow genetic basis. The morphological variability of apomictic species is very limited and is mostly phenotypic (modification). The sexual species of Sorbus s. l. are variable in morphology and include a great diversity of genotypes. Similarly, interspecific hybrids that are diploid (allodiploid) and sexual are treated as a single taxon thus embracing all possible morphotypes of the same origin and at the same ploidy level, as long as there is no evidence of their reproductive isolation (Sennikov and Kurtto 2017).

The status of the Taraxacum group is still little known. Within the Pannonicum, we have recent literature data only for the section Palustria (Kirschner and Štěpánek 1998). However, the exact identification of the majority of the populations living here is still unknown today.

Several endemic apomictic species have also been described from the Ranunculus auricomus group (Soó 1964 b, 1965), but we had no relevant information about them since then, so their current status is unknown. These taxa are accepted as species by the databases “The Euro+Med PlantBase” and “Plants of the world online”. These taxa are therefore presented in a separate list (Presumably endemic Ranunculus taxa, Appendix 4). Research on Ranunculus auricomus group in the Pannonicum has been limited to its western edge in recent decades (e.g. Hörandl and Gutermann 1995, 1998 a, b, c, 1999). The species described and presumed endemic to this marginal area are also presented in this list.

Based on the size of the distribution area I distinguished four basic categories of endemic taxa in the Pannonicum: eurychoric endemics distributed rather evenly throughout the whole Pannonicum or in their major part; mesochoric endemics with distributions restricted more or less to the individual subunits (e.g.: Matricum or Bakonyicum); stenochoric endemics distributed only in a particular mountain or lowland range (e.g. Bükk or Nyírség) and microchoric endemics restricted to a (or sometimes two) particular small area (e.g.: the summit of the Szénások or the bog of Moosbrunn).

Taxa selection and their evaluation

This evaluation includes endemic and subendemic taxa reported from the Pannonicum in literature and database. Special attention was paid to taxonomic publications that contain up-to-date information on endemic taxa of vascular plants. Among some taxonomically difficult taxa (e.g. Alchemilla, Chamaecytisus, Festuca, Rubus, Sorbus), I listed only those with existing relevant information in recent taxonomic literature or those commented on by competent experts. The list does not include taxonomically difficult groups for which it has no or insufficient relevant information: Taraxacum (except sect. Palustria), most of the Hieracium and Rubus taxa or Ranunculus auricomus agg. group (latter presented in a separate list). Distribution data came from literature (see Appendix), internet databases (Database of the Czech Flora and Vegetation: https://pladias.cz/en, Vascular plants of Hungary online database: http://floraatlasz.uni-sopron.hu/index.php?lang=en, Flora Croacia Database https://hirc.botanic.hr/fcd/Search.aspx, Red Data Book of the Republic of Bulgaria Digital edition: http://e-ecodb.bas.bg/rdb/en/), herbarium (Hungarian Natural History Museum, Budapest) and from personal communication. For the evaluation of endemism and classification of endemic taxa, comprehensive taxonomic and chorological studies as well as national floras were preferred. The publications, on which the evaluation of endemism was based, are listed in respective tables in the column “Reference” (Appendix 3).

Plant names mostly follow The Euro+Med PlantBase (http://ww2.bgbm.org/EuroPlusMed/query.asp), the remaining names are used according to the current taxonomic literature. The validity of plant names and their taxonomic status were checked also in supranational databases: The Plant List (http://www.theplantlist.org), Plants of the world online (http://www.plant-softheworldonline.org), World Checklist of Selected Plant Families (https://wcsp.science.kew.org). I also considered authors’ opinions published in current national floras and checklists.

Habitat preferences of (sub)endemic taxa

For further studies I examined the occurrence of endemic taxa in various habitat groups and habitats. I distinguished the following basic habitat groups: (Sal) Saline vegetation; (Sand) Steppe, steppe forest on sand; (Loes) Steppe, steppe forest on loess; (Ro) Rock fissures, rock shelters, shallow rocky solis; (Wet) Wetland communities like bogs, marshlands, alluvial meadows; (Xe) Xerophile/dry grasslands (in general) and shrubs; (Me) Mesic hay meadows and pastures; (XeF) Xerophilic mountain forests (oak and oak scrub forests, rocky forests, etc.); (MeF) Mesophilic forest communities (oak-hornbeam and beech forests, riverine forests, etc.).

Habitat preferences of (sub)endemic taxa were evaluated according to the ecological and phytosociological literature (e.g. Soó 1966, 1968, 1970, 1973, 1980), comprehensive studies of selected genera and species, or the knowledge of competent experts. Habitats less characteristic/ordinary of a given taxon are enclosed in parentheses “()” in the table (Appendix 3).

Non-endemic taxa

77 taxa were evaluated as endemic to Pannonicum in the literature but are not endemic according to current taxonomic and phytogeographical knowledge (Appendix 1). Most of them belong to synonyms of other taxa with a wider distribution. Many of them have wider non-endemic distribution: Artemisia santonicum subsp. patens, Aster tripolium subsp. pannonicus, Bromus pannonicus, Carduus collinus, Centaurium littorale subsp. uliginosum, Cirsium furiens, Dactylorhiza fuchsii subsp. sooana, Dianthus giganteiformis, Elatine hungarica, Galium austriacum, Knautia arvensis subsp. pannonica, Minuartia frutescens, Pilosella budensis, P. megatricha, Plantago schwarzenbergiana, Polygonum graminifolium, Primula auricula subsp. hungarica, Puccinellia distans subsp. limosa, Rhinanthus borbasii subsp. borbasii, Rorippa sylvestris subsp. kerneri, Rosa facsarii, R. zalana, Scilla bifolia subsp. buekkensis, Seseli osseum. In recent times Tilia, Thymus and Mentha genera have since been processed in detail, resulting in a significant reduction in the number of species (e.g. Thymus: Mártonfi 1997). None of them is currently considered endemic.

The Kitaibela vitifolia has only a few data in the Pannonicum (Tatár 1939), and its main area of distribution is in the Balkans (Tunçkol et al. 2020). This list provisionally includes taxa with unclear taxonomic status. For example, Achillea horanszkyi is probably a primary hybrid, but further research is needed (Dobolyi 1997). The taxonomy of Onosma arenaria is not yet clearly resolved but it appears to have wider non-endemic distribution.

Shared endemic taxa of the Pannonicum and western part of the Carpaticum

Some taxa have a narrow range, but can be found in parts of both the western part of the Carpaticum and the Pannonicum. These are not endemic separately in either of the two above-mentioned phytogeographical regions, but they are worth mentioning due to their narrow distribution area. These five taxa show the Appendix 2.

Erysimum wittmannii subsp . pallidiflorum was considered Pannonian endemic (Soó 1968) but according to recent literature, it also occurs in the Carpaticum (eastern part of Slovakia) (Michalková 2002). Ophrys fuciflora subsp. holubyana was considered Western Carpathians endemic but it also occurs in the Transdanubian Mountains (Molnár V. and Csábi 2021). Dianthus plumarius is called “lumnitzeri” in the literature but according to the latest research (Barina et al. 2020), this is the correct name for a taxon that occurs from Hainburg to Malé Karpaty and Inovec Mts. Further research of taxa previously classified as Dianthus plumarius agg. is required. For more detailed information see Appendix 2.

Endemic or subendemic taxa in Pannonicum

Based on current taxonomic literature, databases and consulting with local experts we identified 143 (73 of them apomicts) taxa endemic or sub-endemic to the Pannonicum (Appendix 3). Only 29 of the taxa mentioned by Tatár (1939) are still considered endemic today. Based on the list, 42 of the vascular plants are species, 29 subspecies (both subspecies of Dianthus serotinus are endemic) and another 73 are apomictic taxa. Most of the latter belong to the genus Sorbus (47 taxa) and Taraxacum (23 taxa). (This is the first compilation to include these in detail.) These taxa are analysed separately.

None of the Pannonian endemics are endemic at the genus or a higher taxonomic level. The Rosaceae has the most (sub)endemic taxa: 51 (but 49 of them apomictic), followed by Asteraceae (35 taxa but 24 of them apomictic) (Table 1). Orchidaceae have relatively few species in the Pannonicum but there is a relatively high rate of endemism among them. All of them belong to the genus Epipactis. Large families without endemics are the Cyperaceae and Lamiaceae. At the genus level, the highest number of endemic taxa is found in Sorbus, Taraxacum, Dianthus and Epipactis.

Occurrence of 70 endemic and subendemic taxa (apomictic taxa were omitted from this analysis) grouped according to the size of their distribution area as follows: eurychoric 19 (27%), mesochoric: 27 (39%), stenochoric: 16 (23%), microchoric: 8 (11%).

Eurychoric species in some cases occur in a wide range of habitats throughout the Pannonicum such as xerophil grasslands (Centaurea scabiosa subsp. sadleriana, Dianthus pontederae, Melampyrum barbatum subsp. barbatum) or different types of forests (Epipactis tallosii). Other species occur in two types of habitats: sand steppes in the lowlands and foothills, and rocky grasslands in the hills (Gypsophila fastigiata subsp. arenaria, Iris arenaria). In other cases, some taxa are associated with only one habitat type, but they are widespread in it (e.g. Festuca vaginata on sands). Most of the endemic taxa are mesochoric. Their distribution range is typically (a part of the) the lowlands (e.g. Suaeda pannonica, Festuca wagneri, Limonium gmelini subsp. hungaricum) or mountain ranges: Transdanubian (exactly: Bakonyicum phytogeographical unit) (Seseli leucospermum) or North Hungarian (Poa pannonica subsp . scabra) (with limited occur-rence in the Visegrád Mts). In some cases, a certain part of Pannonicum (Lotus borbasii in the northeast, Paeonia officinalis subsp. banatica in the south). Stenochoric species occur only in a special area of the lowland (e.g. Crataegus nigra, Melampyrum nemorosum subsp. debreceniense, Pulsatilla flavescens), collin region (Chamaecytisus supinus subsp. pannonicus), or a single mountain region (Draba lasiocarpa subsp. klasterskyi). The most exciting are the microchoric taxa. They occur mainly in rocky grasslands (Festuca vojtkoi, Knautia kitaibelii subsp. tomentella, Linum dolomiticum), sometimes in rocky forests (Hesperis matronalis subsp. vrabelyiana) but even in sandy steppes (Centaurea jankeana) or bogs (Cochlearia macrorrhiza).

In terms of phytogeographical units, the number of their own (or shared with another unit) endemics are as follows (apomictic taxa were omitted from this analysis): Eupannonicum 22 (27), Matricum 8 (13), Bakonyicum 6 (13), Praeillyricum 2 (5), Praenoricum: 0 (1) and Thermenlinie 2(1).

The Eupannonicum has most of its own (sub)endemic taxa. Some occur in both lowlands (Great and Little Plain): Centaurea tauscheri, Cirsium brachycephalum, Dianthus serotinus subsp. serotinus (there are also occurrences in the foothills), Galatella cana, Suaeda pannonica and Artemisia pancicii. (The latter has an interesting distribution area as it lives on two opposite edges of the Eupannonicum.) However, most of them live only in the Great Plain. Within this, most of the (sub)endemic taxa can be found in the Duna–Tisza köze region, especially in the part called Kiskunság. Own endemics and subendemics in this area (often shared with Deliblato Sands or surrounding areas): Colchicum arenarium, Dianthus diutinus, Epipactis bugacensis subsp. bugacensis (the only true endemic), Festuca pseudovaginata, F. wagneri, Sedum urvillei subsp . hillebrandtii, Tragopogon floccosus. The northeastern part of Eupannonicum (Nyírség, Bodrogköz) has two endemics of its own: Melampyrum nemorosum subsp. debreceniense (Nyírség) and Pulsatilla flavescens (Nyírség-Bodrogköz). The following areas also have a (sub)endemic species: Deliblato Sands (Centaurea jankeana), floodplains of the Danube (Crataegus nigra) and floodplains of the Tisza (Armoracia macrocarpa). The Little Plain has only two endemics of its own: Cochlearia macrorrhiza and Puccinellia peisonis. Shared endemics of Eupannonicum and Matricum: Onosma pseudoarenaria subsp. tuberculata, Pulsatilla zimmermanni. Shared endemics of Eupannonicum and Bakonyicum: Gypsophila fastigiata subsp. arenaria, Iris arenaria.

The Matricum has 8 (sub)endemic taxa of its own. Most of them (6 taxa) can be found in Bükk Mountains which also has two endemics of its own: Hesperis matronalis subsp. vrabelyiana, Sesleria hungarica (the latter has one locality in Gömör–Torna Karst, but it is rather common on the rocky slopes of the Bükk Mts). The second most endemic-rich area is the Gömör–Torna Karst which has one endemics of its own: Draba lasiocarpa subsp. klasterskyi. These two areas share another endemic taxon, the Dianthus praecox subsp. pseudo-praecox. Noccaea jankae and Poa pannonica subsp. scabra are widely distributed across the Matricum, while Festuca vojtkoi have only a few localities. Shared endemics of Matricum and Bakonyicum: Sempervivum matricum (occurring also in Muranska planina Mts) and Ferula sadleriana (the latter has one locality in the Apuseni Carpathians).

The Bakonyicum has 6 endemic taxa of its own. Dianthus serotinus subsp. kitaibelianus and Seseli leucospermum are quite common and occur throughout this range while Centaurea scabiosa subsp. vertesensis is found only in the central part and Sesleria sadleriana (occurring also in Hainburger Berge) lives only in the eastern part of the area. Two taxa have a very limited range only in the Budaihegység or Pilis: Linum dolomiticum, Knautia kitaibelii subsp. tomentella. Shared endemics of Bakonyicum and Praeillyricum is Vincetoxicum pannonicum.

The Praeillyricum has only 2 endemic taxa of its own. Chamaecytisus supinus subsp. pannonicus occurs in the northeastern hilly part of the area, while Epipactis mecsekensis occurs in the eastern part of the Mecsek Mountains. The largest population of Paeonia officinalis subsp. banatica lives in the Kelet-Mecsek, but can also be found in some localities on the southeastern edge of the Eupannonicum. Chamaecytisus heuffelii occurs in the Mecsek (Praeillyricum) in Deliblat (Eupannonicum) and in the Iron Gate Gorge (Southern-Carpathians).

The Thermenlinie area has 2 endemic taxa of its own: Centaurea scabiosa subsp. badensis, Dianthus plumarius subsp. neilreichii. Shared endemics of Thermenlinie and Praenoricum is Festuca stricta subsp. stricta.

The number of Pannonian (sub)endemic taxa (apomictic taxa were omitted from this analysis) in different phytogeographical units is as follows: Eupannonicum 47 (67%), Bakonyicum 34 (49%), Matricum 28 (40%), Praeillyricum 22 (31%), Praenoricum 6 (9%) and Thermenlinie area 7 (10%).

Five endemic taxa occur in the area between the Drava and the Sava river, which can be considered a transitional area from a phytogeographical point of view. These are the following: Achillea asplenifolia, Dianthus collinus subsp. c ollinus, D. pontederae, Epipactis nordeniorum, Melampyrum barbatum subsp . barbatum. They are quite sporadic here.

Occurrence of 47 endemic Sorbus taxa grouped according to the size of their distribution area as follows: eurychoric 0, mesochoric: 6 (13%), stenochoric: 18 (38%), microchoric: 23 (49%). Only six Sorbus taxa have mesochoric distribution, five of which live in the North Hungarian Mountains and another one in the Transdanubian Mountains. Most of the taxa have microchoric distribution. Many species occur in a single mountain gorge, summit, or northern slope of the valley. Endemic Sorbus taxa occur only in the Transdanubian Mountains (Bakonyicum: 39 taxa) and in the North Hungarian Mountains (Matricum: 8 taxa). The most diverse areas are Vértes (16 taxa), Bakony (14 taxa) and Gömör-Torna Karst (8 taxa).

The exact distribution of endemic Taraxacum species is little known, especially in Hungary, Serbia and Romania. Most of the records of the species are based on (sometimes old) herbarium specimens. Most of the plants observed in the field were identified as T. palustre agg. (e.g. Bartha et al. 2021). Based on our current knowledge there are only two microcoric species among them (T. catenatum and T. limosicola). Most of them are steno-, meso- or eurychoric. They typically occur in lowlands and valleys. The main distribution area of endemic Taraxacum species is the Eupannonicum. The records from Praeillyricum came from wetlands in the southern part of the Lake Balaton area.

The other three apomictic taxa are stenochoric (Alchemilla hungarica, Hieracium kossuthianum) or mesochoric (Rubus balatonicus). The latter two occur in the Bakonyicum (Rubus balatonicus lives in the western and central parts of this area while Hieracium kossuthianum occurs only on the eastern margin of the area) and the former in the Matricum.

Habitat preferences of (sub)endemic taxa

Most endemic (not apomictic) plants occur in rocky (27%) or sandy (20%) habitats (Fig. 2). Together with the taxa that occur in both habitats, a total of 53% of the plants studied live here. Most of them are on calcareous soil. Only two taxa occur in acidic soils in both sandy (Melampyrum nemorosum subsp. debreceniense, Pulsatilla flavescens) and rocky (Festuca vojtkoi, Sempervivum matricum) habitats, but the latter can also be found on calcareous soils. Another 9 taxa (13%) live in different types of xerophilic grasslands (in general) or shrubs and a further 2 (3%) mainly on rocks, but often also in rocky forests. Most of the (sub)endemic taxa (54 of them, 77%) live in dry habitats mentioned so far. There are only 2 species in wetlands, 4 in saline vegetation, and 2 in saline meadows. There is only one subspecies among them, so it seems that most endemics have developed in these habitats for a long time.

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Habitat preferences of Pannonian (sub)endemic taxa (without apomictic taxa). Sal = saline vegetation; Sand = steppe, steppe forest on sand; Loes = steppe, steppe forest on loess; Ro = rocks, rocky grasslands; Wet = bogs, alluvial meadows and other wetland communities; Xe = xerophile/dry grasslands (in general) and shrubs; XeF = xerophilous mountain forests (oak and oak scrub forests, rocky forests, etc.); MeF = mesophilic forest communities (oak-hornbeam and beech forests, riverine forests, etc.)

Citation: Acta Botanica Hungarica 65, 1-2; 10.1556/034.65.2023.1-2.8

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The extraordinary richness of rocks and rocky grasslands is not surprising, but the extraordinary richness of sandy habitats is interesting. Within the Pannonicum, there are significant differences in vegetation (and endemic species) on sandy soils. One of the main sandy area is situated in the southwestern part of Transdanubia (Belső-Somogy). Its climate is relatively humid (average annual rainfall 700–750 mm) (Bihari et al. 2018). The natural vegetation here is the forest (oak, oak-hornbeam, beech), and sand steppes are very rare and fragmented (Zólyomi 1989). This area has no endemic taxa of its own and only two of the endemic taxa of the Pannonian sand occur here (Dian-thus serotinus subsp. serotinus, Festuca vaginata). Another important sandy area (this sand is acidophilus) is located in the northeastern part of the Pannonicum (Nyírség and some surrounding areas). The climate is drier here (average annual rainfall 550–650 mm) (Bihari et al. 2018). The main natural vegetation is steppe and forest-steppe (Zólyomi 1989). This area has two endemic taxa of its own (Pulsatilla flavescens and Melampyrum nemorosum subsp. debreceniense), and many other endemics can be found here (e.g. Dianthus serotinus subsp. serotinus, Festuca vaginata, Iris arenaria). The most important sand vegetation is found along the Danube, including its wider surroundings from southern Moravia to Deliblat. There are several sand areas here, which are more or less separated from each other. They are found in the hottest and driest areas of the Pannonicum. The average annual precipitation is 450–650 mm (Bihari et al. 2018, Milovanović et al. 2017, Tolasz et al. 2007). The main potential natural vegetation is steppe and forest-steppe (Chytrý 2012, Niklfeld 1973, Schratt-Ehrendorfer 2008, Zólyomi 1989). The most endemic-rich area is in the Duna–Tisza köze region, which is in the middle of the Pannonicum. This area, whose soil is mostly calcareous sand, has only one endemic taxon of its own (Epipactis bugacensis subsp. bugacensis), but it is the centre of the distribution area of many endemics. Similar but not so species-rich sand flora can be found in the Mezőföld (on the opposite side of the Danube), and in the eastern half of the Little Plain (on both sides of the Danube). Farther away, on the sand steppes of South Moravia (the northwestern part of Pannonicum), only a few endemics can be found. The Deliblat, located in the southeastern corner of the Pannonicum, is also rich in endemics. This area has one endemic taxon of its own (Centaurea jankeana). Some endemic species appear on the sand dunes of the lower part of the Danube, outside of Pannonicum, but not far from it.

These “Pannonian flora islands” have more Pannonian endemics than on the sands of South Moravia.

Only two endemic subspecies (Chamaecytisus supinus subsp. pannonicus, Cirsium boujartii subsp. boujartii) are restricted to the species-rich Pannonian loess steppes. Some authors (Fekete et al. 2014) also list the Noccaea jankae here, but this species often occurs in other habitats as well (Illyés and Bölöni 2007). In loess steppes, however, there are plenty of (sub-)Pontic-Pannonian elements. Of course, there are endemics in loess steppes as well, but these have fallen into the “xerophilous grasslands” category here.

Xerophilic mountain, sometimes grassy mosaic forests have only 4 (sub) endemic taxa (6%). Most of them were not widespread in Pannonicum. Some taxa occur only in the north (Chamaecytisus virescens), south (Paeonia officinalis subsp. banatica) or northeast (Galium abaujense). Mesophilic forest communities have 8 (sub)endemics (11%). Most of them are Epipactis species. Habitat grouping does not show, but some taxa (Cirsium brachycephalum, Melampyrum barbatum subsp. barbatum, Noccea jankae) also occur in segetal weed communities.

Among apomictic taxa (not listed in the table) most of the endemic Sorbus species prefer xerophilic mountain forests (oak and oak scrub forests, rocky forests), but some also live in mesophilic forests. Endemic Taraxacum species live in wet (sometimes saline) meadows and other wetland communities. The other three species live in rocks or edges of the xerophilic mountain forests (Hieracium kossuthianum, Rubus balatonicus) or mountain mesic hay meadows and pastures (Alchemilla hungarica).