Lathyrus L.: the distribution, habitats and remarks on the status of the species in Poland

in the flower size, the corolla colour and the number of flowers per peduncle observed in specimens of the species. Abstract Lathyrus aphaca , which is in Poland considered to be an ephemerophyte recorded mainly in the north-west and the south-west, has lately been observed in arable fields in the south of the country. Recent and historical data on the distribution of the taxon in Poland are presented. Original relevés conducted in arable fields in Poland are analysed and compared to those from the Czech Republic, Germany and Slovenia. The current status of L. aphaca in the Polish flora is discussed.


Introduction
Lathyrus aphaca is a species of Mediterranean-Irano-Turanian origin.At present, the species mostly occurs in Western and Southern Europe, southern part of Central Europe, northern parts of Africa as well as in South-Western and Central Asia [1][2][3][4].Reports on the introduction of L. aphaca to North America are also available [5,6].
According to Rostański and Sowa [7], Lathyrus aphaca is an ephemerophyte in Poland, that is an alien species introduced transiently and not established permanently.The same status was later proposed for the species by Mirek et al. [8,9].However, field studies carried out by us in 2007-2009 suggest that L. aphaca may be established in some regions of Poland.

Description of the species
Lathyrus aphaca L. [= Lathyrus segetum Lam., Aphaca vulgaris C. Presl., Orobus aphaca (L.) Döll.; English: yellow pea, yellow-flowered pea or yellow vetchling; Polish name proposed by us: groszek bezlistkowy] is an annual plant species with scrambling or trailing stems up to 100 cm long.Mature leaves of the plant have no leaflets.They are only composed of ovatehastate stripules (0.6-5 cm × 0.5-4 cm) and tendrils.Stems bear some solitary flowers.The peduncle linking the flower to the stem is 20-50 mm long.Flowers are 7-13 mm long.Calyx teeth are 2-3 times as long as the tube.The corolla is bright yellow, sulphur or cream.Legumes are glabrous, straight or incurved, 2-3.5 cm long and 0.3-0.8cm wide, with 6-8 seeds.Seeds are ellipsoid to globose, usually flattish with a glossy, smooth, dark purple-brown to black surface, sometimes spotted to marbled.Chromosome number: 2n = 14 [2,4,10,11].
A number of varieties were distinguished based on the differences in the flower size, the corolla colour and the number of flowers per peduncle observed in specimens of the species.The Lathyrus aphaca complex reaches its maximum variability in Anatolia [2].

Habitats of Lathyrus aphaca
Within its natural range, Lathyrus aphaca is recorded in natural habitats (mainly rocky limestone slopes, stream banks, and plant communities representing the formation described as phrygana in the eastern regions of the Mediterranean area), in semi-natural meadows and glades, as well as in arable fields, on fallow lands and roadsides [2,3,12].Within the anthropogenic part of its range in Europe, L. aphaca was observed in a different type of habitats, e.g. in the vegetation of forest edges representing the Trifolio-Geranietea sanguinei class, on dry lawns, transport route edges (especially along railway lines), in orchards, arable fields and fallows [4,13].
Phytosociologically, Lathyrus aphaca is a diagnostic species of segetal communities in cereals and legume-grain mixtures (preferably winter cultures) and winter rape in warm areas of the temperate to submeridionale zones of the Euro-Siberian region representing the Caucalidion lappulae alliance [14].
Research on the occurrence of Lathyrus aphaca in plant communities was conducted in 2007-2009 at the same sites, i.e. in three arable fields in the southern part of Kraków.The Braun-Blanquet method was used in phytosociological investigations [15].A total of eight phytosociological relevés were performed.The area of each relevé was the same (2 m × 10 m).Their location was determined using a GPS receiver (the WGS84 coordinate system).
The relevés with Lathyrus aphaca from Kraków were compared with those from three other countries: 12 relevés from the Czech Republic [16], one reléve from Germany [17] and 17 relevés from Slovenia [18].The SYN-TAX 2000 software package [19] was used for numerical analysis.

The occurrence of Lathyrus aphaca in Poland
The list below comprises all the localities of Lathyrus aphaca recorded in Poland to date.Their locations are given using the ATPOL grid square system of 10-km cartogram units [20].The habitat (if specified in the source), the author's name and the publication/collection date are given for all the records.The standardised abbreviation of the hosting herbarium is added for herbarium data.ZACHODNIOPOMORSKIE VOIVODESHIP.AB25: Kamień Pomorski, no habitat data; according to Holzfuss [21], Weicker collected Lathyrus aphaca at this locality in 1912 (but the herbarium material is not available in any Polish herbarium).AB83: Szczecin -Gdańska Str., rubble heaps; Holzfuss [21] collected the plant at this locality in 1936 (but the herbarium material is not available in any Polish herbarium).Szczecin -Gdańska Str., rubble heaps; according to Scheuermann [22], the plant was repeatedly brought into this locality with cereals.AB93: Siadło Dolne near Szczecin, no habitat data; Holzfuss [21] collected the plant at this locality in 1935 (but the herbarium material is not available in any Polish herbarium).PO-MORSKIE VOIVODESHIP.DA80: Gdańsk -Westerplatte, N-Port and Wisłoujście, squares and tipping sites for ballast soil in the port; according to Abromeit et al. [23], Bail collected the plant at this locality in 1879 (but the herbarium material is not available in any Polish herbarium).DOLNOŚLĄSKIE VOIVODESHIP.BE13: Buczynka near Lubin, arable field (Secale cereale culture); Schube [24].BE32: Lipce near Legnica, no habitat data; Schube [24].BE48: Wrocław -city port, rubbish tips near a mill; according to Meyer [25], the plant was brought into this locality with barley imported from Southern Europe and Morocco.BE48: Wrocław, tracks (exotic fruit handling site) and near a covered market; Meyer [26].BE49: Wrocław -the yard by the covered market in Tęczowa Str.("Siebenhufener Strasse") used for storage of fruit from Southern Europe; Schalow [27] collected the plant at this locality in 1931 (but the herbarium material is not available in any Polish herbarium).BE49: Wrocław -between the Zacisze and Kowale estates, no habitat data; according to Schalow [28], Becker collected the plant at this locality in 1932 (but the herbarium material is not available in any Polish herbarium).BE58: Wrocław -western freight station, rubbish tips and tracks; according to Meyer [29], the plant was brought into this locality with cereal and citrus fruit.BE59: Wrocław -Tarnogaj, no habitat data; according to Schube [30], Behnsch collected the plant at this locality in 1900 (the herbarium material is deposited in WRSL).BE60: Jelenia Góra -Skowronków, no habitat data; according to Schube [30,31] Fiek collected the plant at this locality in 1900 (but the herbarium material is not available in any Polish herbarium).BE75: Świdnica -by the road towards Wałbrzych; according to Schube [32], Wildner collected the plant at this locality in 1904 (the herbarium material is deposited in WRSL).OPOLSKIE VOIVODESHIP.CF17: Strzelce Opolskie, no habitat data; Michalak [33] collected the plant at this locality in 1973 (but the herbarium material is not available in any Polish herbarium).CF34: Głogówek, a rubbish tip near a brickyard; Szotkowski [34] collected the plant at this locality in 1974 (but the herbarium material is not available in any Polish herbarium).ŚLĄSKIE VOIVODESHIP.DF30: Gliwice -a river port, on rubbish tips near warehouses with packaged cargo; Szotkowski [35] collected the plant at this locality in 1967 (the herbarium material is deposited in KTU).MAŁOPOLSKIE VOIVODESHIP.DF 79: Kraków -Kobierzyn, the plant was observed as a weed in cereal cultures by A. Nobis and M. Nobis in 2007, 2008, 2009 and 2010 (the herbarium material is deposited in KRA).
Lathyrus aphaca has been rarely recorded in Poland.Until 2006, it was reported from a total of twenty localities in seventeen 10-km ATPOL grid squares.The plant was recorded a few times at some of the localities.It was mostly observed in northwestern and south-western Poland (Fig. 1).Over 80% of the reports on the plant's occurrence in Poland date from before World War II.Published data show that it was recorded only in the Śląskie and Opolskie voivodeships after World War II.L. aphaca has been recorded on rubble heaps and waste dumps in river ports.It has also been observed at tracks (at cargo handling sites) and near covered markets where it was brought in with cereals imported from Southern Europe and hay used to protect citrus fruit from frost and mechanical damage.Single localities in arable fields and on ballast soil tips have also been reported.No habitat data are often available for many of its historical localities.

Ch. Stellarietea mediae:
Myosotis arvensis The field studies conducted by us suggest that Lathyrus aphaca is locally established in Poland.It has been observed in arable fields in the southern part of Kraków in the last few years.The species has been reported in crops of wheat, oat and barely, and in their mixtures.Specimens of L. aphaca were recorded both on the margins and in central parts in each of these fields.They were not, however, distributed uniformly but formed small agglomerations, mainly at field margins.The abundance of its populations in individual fields ranged from over fifty to ca. 200 specimens.The plant was not recorded outside these fields, that is in nearby meadows and wastelands, on baulks or roadsides, despite special investigations.Although the size of patches with L. aphaca documented by us was relatively small, the relevés were quite rich in species (Tab.1).From 25 to 31 species were recorded in a single relevé.The coverage of L. aphaca in the patches ranged between 1% and 5%.As relevés were repeated in the same arable fields in successive years and the fields are located close together, the species composition is similar (Fig. 2).Apart from L. aphaca, four other species were observed in all relevés: Myosotis arvensis, Polygonum aviculare, Viola arvensis and Galium aparine, while the highest constancy was also observed for seven other taxa (i.e.Anagallis arvensis, Avena fatua, Centaurea cyanus, Equisetum arvense, Setaria pumila, Veronica arvensis, Veronica persica).As there is an evident contribution of a number of weeds attached to fertile alkaline soils (i.e.Avena fatua, Euphorbia exigua, Geranium dissectum, Lathyrus tuberosus, Sherardia arvensis, Valerianella dentata, Valerianella rimosa) in our relevés, all of the  Tab. 1 (continued) relevés represent plant communities of the Caucalidion alliance.In the patches documented with relevés, the highest constancy is recorded for not only plants typical of communities of arable fields representing the Centauretalia cyani order, the Polygono-Chenopodietalia order or generally the Stellarietea mediae class but also ruderal species typical of the Artemisietea class commonly occurring in arable fields.Bryophytes were not observed at any of the patches documented with relevés.Czech relevés were conducted in wheat, rye, barley and oat cultures to document the contribution of Lathyrus aphaca in segetal communities [16].In Slovenia, relevés where Lathyrus aphaca is a wheat weed dominate; however, relevés were also carried out in barley cultures [18].
The highest contribution of species belonging to the Caucalidion alliance is recorded in the relevés from the Czech Republic.A constancy of over 50% was observed for Lathyrus aphaca as well as for the following species representing the Caucalidion alliance: Adonis aestivalis, Avena fatua, Consolida regalis, Euphorbia exigua, Galium spurium, Lathyrus tuberosus and Ranunculus arvensis [16].A greater number of species of the Caucalidion alliance also occurs in relevés from Slovenia; however, Legousia speculum-veneris was the only species recorded in over 50% of the relevés [18].Eight species of Caucalidion alliance, i.e.Avena fatua, Euphoria exigua, Kickxia elatine, Kickxia spuria, Sherardia arvensis, Silene noctiflora and Stachys annua, were recorded in the only available relevé with L. aphaca from Germany [17].Unlike the relevés from Poland, the presence of meadow species of the Molinio-Arrhenatheretea class and Arrhenatheretalia order is observed in relevés from both the Czech Republic and Slovenia (Tab.2).
An analysis carried out using the SYN-TAX 2000 software package [19] -UPGMA clustering method, 1/0 (presence/absence) data, Jaccard coefficient -shows that the relevés from Poland (Nos.1-8) and relevés from Slovenia performed in arable fields (in cereal cultures) in the central and south-eastern part of the country (Nos.[21][22][23][24][33][34][35][36][37] are most similar to each other.One relevé from Germany (No. 38) and 11 relevés conducted in the Czech Republic (Nos.10-20) constitute the next distinguishable group.The similarity coefficient between this group and the group of all relevés from Poland and Slovenia is only slightly lower than that between the relevés from Poland and the inland part of Slovenia.The highest dissimilarity is observed for one relevé from the Czech Republic (No. 9).The relevé was conducted in a plant community patch with a high contribution of meadow species and trees.Moreover, relevés from Slovenia performed in areas near the Mediterranean coast are grouped separately.Some of them were conducted in cereal cultures (Nos.25-28) while the remaining ones in nurseries (Nos.[29][30][31][32].

Discussion
In Western and Central Europe, Lathyrys aphaca occurs mostly in regions characterised by a comparatively warm and dry vegetation period as well as the presence of the alkaline substrate rich in calcium.As such climatic and soil conditions are also recorded in some regions of Poland, especially in the highlands in the south (Wyżyna Lubelska Upland and Wyżyna Małopolska Upland), it seems surprising that the occurrence of L. aphaca has not been reported from these areas.
established in the Kraków area.It is observed here each year even though cultivated plants change in successive years.As in other European countries, it also occurs in Kraków in its typical habitat, i.e. in arable fields, as a component in communities of field weeds resembling the Caucalidion alliance.While L. aphaca has the status of an archeophyte in the neighbouring countries such as Germany or the Czech Republic [36,37], it should be treated as a local epoecophyte in the flora of Poland.
It should be stressed that a drop in the number of Lathyrus aphaca localities has been observed in some central European countries for many years as the weed flora is greatly influenced by intensively developing technology.Therefore, the species is included on national red lists.L. aphaca is considered to be threatened in Germany or even strongly threatened in some parts of it [38].It is a critically threatened species in the Czech Republic [39], threatened in Slovakia (EN according to the IUCN criteria) [40], and near threatened in Hungary (NT according to the IUCN criteria) [41].
Recently, arable fields in the southern part of Kraków have been extensively managed and Lathyrus aphaca does not seem to be threatened by growing technology.However, the localities can soon be destroyed by the progressive development of the city, and especially by numerous building investments.A discontinuation of cultivations can also pose a threat to the existence of the species.

Fig. 1 A
Fig. 1 A distribution map of Lathyrus aphaca L. in Poland; black circle -locality at which the species was recorded as an ephemerophyte, black square -locality where the species is an established component of the flora.