Phenotypic variability of Cypripedium calceolus L. (Orchidaceae) on its northern distribution bound

The phenotypic variability of Cypripedium calceolus L. (Orchidaceae) growing on the northern bound of its distribution in territory of the Komi Republic is described. It is revealed that miniaturization and oligomerization of plants of this species occurs on the northern bound of distribution, compared to specimens growing in the center of the area. The characters of vegetative sphere demonstrate high and medium variation, but flowers morphology is less variable. Weather conditions influence the habitus of plants which is expressed in the size of leaves and bracts and height of shoots. The weather has no effect on number of flowers and leaves. The correlation of characters is increased in unfavourable growing periods. In plants growing in different biotopes the variability of morphometric characteristics caused by ecological differences is observed. Thus plants from forest habitats were larger than specimens growing in swampy areas due to the lack of light in forest phytocenoses. Besides, geographical variation was revealed in studied populations: gradual reduction of plants habitus within latitudinal moving from south to north. The most flexible characters which respond to changing environmental conditions are the height of shoots and size of leaves.