Study of isolated populations of the water caltrop Trapa sibirica Fler. (Lythraceae) in the Republic of Bashkortostan

The water caltrop (Trapa L.) is a rare and relict annual aquatic plant from the family Lythraceae. Its fruits are edible and contain a lot of starch and protein. In the Republic of Bashkortostan, the water caltrop grows only in two small lakes Upkankul and Bilgilyar. The purpose of our study was the analysis of the water caltrop populations in these two lakes in 2017 and 2018, morphological and molecular-genetic analysis of plants from different points of these lakes, and introduction of the water caltrop seeds in the nearby lakes. The population size in Lake Upkankul in 2017 was the biggest in the last 60 years - 5722 floating rosettes, most of them growing on the eastern side of the middle part of the lake. In the lake Bilgilyar, we found only 28 plants in one single point in 2017. The next year population size in Upkankul decreased by more than two thousand rosettes, and in lake Bilgilyar it slightly increased. Morphometric analysis of fruits of water caltrop of the lake Upkankul showed high similarity with Transbaikalian populations of Trapa L. RAPD and ISSR analyzes confirmed that only one species, supposedly T. sibirica Fler., in growing in these two lakes. A study of 15 nearby lakes has shown that some of them are suitable for introduction of a water caltrop. We collected and stratified the Trapa L. seeds and introduced them in several lakes in the southern part of the Nurimanovsky district of the Republic of Bashkortostan.