Rheum rhaponticum
Rheum rhaponticum L.
Polygonaceae - Knotweed family
Conservation status. Critically Endangered [CR B1ab(ii,v); C2a(i)]. IUCN (R), BDA, BC. Bulgarian endemic. Glacial relic.
Morphology and biology. Perennial herbs with long, massive root. Stem 1–1,5 m high, hollow, glabrous. Basal leaves very large, up to 30 cm in diameter, with long petioles; cauline leaves with shorter petioles, uppermost smaller, sessile. Panicle pyramidal, diffuse. Flowers white or greenish, perianth with 6 segments. Nut dark brown, with rather narrow wings. Fl. VI–VIII, fr. VIII–IX. Reproduction by seeds and vegetatively.
Habitats and populations. Wet grassy, silicate or calcareous stony places along streams in Rila Mts. The population is fragmented and consists of single to several tens of individuals. Because of the avalanche in Beliya Ulei near Rila Monastery the number of the individuals and the population area have been reduced (20 individuals in 2002).
Distribution in Bulgaria. Rila Mts (northwestern and central); 1700 up to 2500 m alt.
General distribution. Bulgaria.
Threats. Aridisation of the climate, avalanches, small number of individuals in the population.
Conservation measures taken. Protected species according to the national Biodiversity Act. The localities are in the borders of Rila National Park and Rilski Manastir Nature Park as well as in a site of the European ecological network Natura 2000 in Bulgaria.
Conservation measures needed. Investigation of the numerical strength and area of the population, and the biology and ecology of the species. Collection of seeds for the National Seed Genebank of Bulgaria.
Note. Because of the very large cultivation in Europe and the existence of the close Siberian and middle Asian species, the natural origin of Rheum rhaponticum in Bulgaria has not been definitely confirmed.
References. Valev 1966; Stanev 1984; Libert & Englund 1989; Ganchev 2006.
Authors: Dimitar Peev, Sonya Tsoneva
