Microsporogenesis of Betula oycoviensis Bess. and of its progeny

Abstract

The crossing of two specimens of Betula oycoviensis Bess. described as a separate taxon of the subsection Albae, unexpectedly yielded a progeny among which three types were distinguished: oycoviensis, verrucosa, and nova, in the approximate ratio 1:2:1. The first two types were trees, whereas the third one was a small shrub. Moreover, the three types of birches differed from one another in a number of morphological and biological characters. Microsporogenesis was in vestigated in the parental specimens of B. oycoviensis and in several specimens of the progeny representing three types of birches. It was only one birch of the oycoviensis type, a mixoploid specimen, that exhibited disturbances in microsporogenesis. In the other examined birches of the oycoviensis, verrucasa, and nova types meiosis 'proceeded normally and resulted in normally developed tetrads an-d pollen grains. Therefore, B. oycoviensis belongs to hybrids of regular meiosis, its hybrid character being revealed only at crossing.