Preliminary results of grid mapping of flora of Udomlya district of Tver region

In june–july 2006 – 2010 we conducted grid mapping of Udomlya district of Tver region (about half of the district was investigated). Distribution of 648 vascular plants species was characterized, including 13 invasive ones (from Black book of Middle Russia). Substantial heterogeneity of the species’ distribution on the investigated territory was revealed. We did not manage to find any universal influence of abiotic factors on the species’ distribution. A number of new and rare species for the region were detected. We revealed new locations of 30 species, listed in regional Red Book, including Epipogium aphyllum Sw. (the species near extinction).