On the ecology and distribution of Trapa natans L. in Lakes of the Tver Region

Abstract

440 The water chestnut, Trapa natans L. (Trapaceae Dumort.) is a Tertiary relict whose fate is a matter of major concern. This plant is listed in the Red Data Books of the Soviet Union (Krasnaya kniga..., 1984) and the Tver Region (Krasnaya kniga..., 2002), where it has the status of species decreasing in abundance. The water chestnut grows in slowly flowing or still water bodies, in well warmed areas protected from wind. Its geographic range extends over the Mediter ranean, central and eastern Europe, central and southern Asia, North America, and Australia (Belous ova et al., 1979). Its range within the boundaries of the former Soviet Union is disjunctive and includes Euro pean Russia, the Caucasus, Transcaucasia, Siberia, Altai, Belarus, Ukraine, and Kazakhstan (Vasil’ev, 1952). Within this vast range, the species is sparse and occurs sporadically mainly in floodplain lakes, oxbows, river inlets, etc. with depths of 0.5–2 m (Vasil’ev, 1960; Lisitsina, 1993).