Carex disperma Dewey versus Carex loliacea L. (Cyperaceae): distribution dynamics and conservation status in Poland

Carex disperma Dewey reaches its south-eastern range limit in north-eastern Poland. It has often been confused with Carex loliacea L. In this paper the diagnostic features of both species are presented. A total of about 47 reliable localities of C. disperma were recorded within the present borders of Poland. Less than one-third of them have only been confirmed recently. They are aggregated in large forest complexes in north-eastern Poland (Romincka, Białowieża, Borki, Augustów and Knyszyn Forests). A list of localities of C. disperma based on herbarium records, credible literature data and the author's own data is provided, as well as maps of distribution of both C. disperma and C. loliacea in Poland. The existence of C. disperma × C. loliacea hybrid was not confirmed. Considering the number of localities, dynamics and population sizes of both species it is clear that C. disperma is a species with higher conservation value than C. loliacea. Unlike C. disperma, the latter species is not threatened with extinction in Poland. The resources of C. disperma are very limited and the species needs conservation measures such as creating sufficiently large nature reserves where appropriate hydrological conditions can be maintained.