CHROMOSOME VARIATION AND EVOLUTION IN TRILLIUM GRANDIFLORUM

Abstract

Chromosome analyses using cold-induced banding patterns were carried out on 25 wild populations of Trillium grandiflorum (Michx.) L. throughout the natural range of the species. Banding patterns were fairly uniform within and between populations with the exception of those occurring in chromosome D which varied from three to five times more than the other chromosomes. This is different from the situation in the western North American species T. ovatum Pursh. in which chromosome C is the most variable and the Japanese species T. kamtschaticum Pall. in which chromosome A is the most variable. There was greater homogeneity of karyotypes in northern populations than in southern ones. Supernumerary chromosomes were found in four of the 25 populations. In one plant the karyotype had been altered by a spontaneous translocation which has produced two new chromosome variants.