Although the knowledge of pollination systems of rare and threatened species is one of the principles for development of optimal conservation and management strategies, the data about their pollination requirements are scarce or incomplete. Different problems are listed (xerothermic habitat disappearance, overgrowing of patches, plant biology i.e., slow plant growth, problems with seed germination) among the possible causes of Adonis vernalis being threatened, but until now no consideration was given to the flowering biology and pollination.The observations of flowering biology of A. vernalis (Ranunculaceae), a clonal species, were conducted in an out-ofcompact-range population, in the Lublin Upland, Poland (51°18'55" N, 22°38'21" E), in 2011-2013. The reproductive potential of A. vernalis is related to the population age structure, pollination syndrome, and breeding system. The flowers exhibit incomplete protogyny. The dichogamy function is supported by different (biological, morphological) mechanisms. Stigma receptivity occurred about one day before anthers started shedding self-pollen, and pollen viability was increasing gradually during the flower life-span (66.3% in distal anthers vs. 77.3% in proximal). The decrease in pollen production and in pollen viability coincided with the lowest degree of seed set, irrespective of the pollination treatment. Pollen vectors are necessary for efficient pollination, as the proportion of pistils setting fruits after open pollination (41-82.1%) was significantly higher compared to spontaneous self-pollination (only 5.5-12.3%). The pollination requirements together with pollen/ovule ratio (P/O = 501) indicate a facultative xenogamous breeding system in A. vernalis. Therefore, in the conditions of the global lack of pollinators, improper pollination may weaken the population by leading to a decrease in the proportion of recombinants, and in addition to other factors, may accelerate extinction of small A. vernalis populations.

The distribution of the genus Orobanche in SE Poland is presented. The study area stretches between the Vistula and the Bug rivers, and comprises the Polish areas of the Lublin-Lwów Upland, the Wołyń Upland and the southern part of Polesie.

Viola uliginosa Besser is a European species mainly known from the Baltic Region. It is endangered in a significant part of its range. Research carried out in the southeastern part of Poland led to the discovery of numerous sites of Viola uliginosa. Fourteen new localities of this species were found in the area of the Kotlina Sandomierska basin. This paper presents information concerning the localization of all new sites, the abundance of Viola uliginosa at the sites and habitats this species occupies. A discussion regarding the endangered status of this species in the Polish flora is given.

The aim of this study is to present the updated list of rare and threatened vascular plant species in the Lublin province. The threatened species categories are presented according to the IUCN criteria. The regional list contains 408 species (that makes up 25% of the Lublin Region flora); 56 of which are considered critically endangered, 81 represent endangered species, 51 belong to the category of vulnerable species, and 49 are near threatened species, respectively. The presence of 37 species has not been confirmed and therefore they are listed as regionally extinct (RE). Of the total number of species, 134 are rare, but because the data about those species is insufficient, they have been classified as DD category (data deficient). The species of the genera: Alchemilla, Callitriche, Hieracium, Oenothera, Rosa, Rubus and Taraxacum have not been evaluated (NE category). Other species – those whose occurrence is doubtful and all neophytes were defined as not applicable (NA). The endangered taxa occur mostly in dry grasslands, deciduous forests, wetlands, and calcareous weed communities of cereal crops.

S u m m a r yThe number of Adonis vernalis populations, their size and abundance in xerothermic communities of the Lublin Upland have decreased signifi cantly in the last 40-50 years, which indicates that there is a real risk of species extinction in the studied area. The paper is an attempt to indicate the possible factors which infl uence the decrease of Adonis vernalis populations. Detailed studies were carried out in six sites differing habitat conditions, land use and the size of Adonis vernalis populations. Observations were made of the abundance of blooming and the number of anthers per fl ower. The ability for reproduction was estimated indirectly by the mass of pollen delivered and its biological value. The populations of Adonis vernalis differ in number of anthers per fl ower (94.4 -131.5, on average), the mass of pollen delivered (0.83 mg -3.18 mg per 100 anthers, on average), the biological value of pollen and the size of pollen grains. Generally, stronger populations were characterized by better quality and a higher quantity of pollen. Potential energy of pollen in fl owers from Pliszczyn and Łabunie was 69-72%, compared to 36%-47% in the remaining populations. Grass burning did not cause a reduction of potential biological value of Adonis vernalis pollen. Xerothermic swards in Pliszczyn and Kąty regularly burnt developed strong, most abundant populations of Adonis vernalis with favorable pollen. The development of the shrub layer, if it is out of control, stands in the way of satisfactory reproduction of halophilous Adonis vernalis.