Drosera in Ukraine: ecological, chorological specifics and phytosozonomical characteristics.
The paper presents a chorologically systematized description of all taxa of the Drosera L. genus in Ukraine. We performed an analysis of environmental conditions, phytocoenotic characteristics and found new locations of sundew. We generalized the morphometric parameters and proposed a concept - "leaf roundness index"; and recommended including Drosera rotundifolia, Drosera x obovata in the next edition of the Red Data Book of Ukraine due to the contraction of their habitat and their high degree of vulnerability to unfavourable environmental factors and anthropogenic impact; we recommend growing Drosera ex-situ on the example of Kremenets Botanical Garden with further repatriation in-situ; proved the efficiency of the proposed methods of farming cultivation. The paper substantiates the complex of phytosozological criteria, measures for protection and reproduction of the endangered species of Drosera genus. We suggested a hypothesis about the independence of the taxon of Drosera x obovata. Despite the fact that Drosera longifolia x D. rotundifolia is generally considered to be sterile hybrid, individuals breed vegetatively, are fertile and retain germinability after germination, and have a clearly specific ecotype, sometimes loci are isolated from parent species. To isolate the Drosera x obovata as a single taxon, additional phylogenetic studies are needed, but as a rare, disappearing taxon it needs protection and background monitoring of populations. The area of greatest phytosozological value for sundews in Ukraine is Western Polissia (Volyn, Rivne regions) (D. longifolia - 31, 20 sites, D. intermedia - 31 and 30 respectively). Drosera longifolia is on average distributed slightly further south in Ukraine than D. intermedia, although both taxa are confined to the humid, boreal zone. D. rotundifolia is most widespread in the humid zone (Polissia, the Carpathians). Despite the presence of Drosera x obovata in the Cheremskyi, Rivnenskyi Nature Reserve, Shatskyi National Nature Park, and several landscape reserves, the taxon is continuing to disappear due to succession, afforestation, water regime change etc.