The purpose of this paper is to provide information concerning the number, structure, and behavior of chromosomes in the plant species Fritillaria atropurpurea. The material used for this investigation included both floral buds and root-tips from actively growing naturally occurring plants collected from populations in both Utah and Nevada, and root-tips from seed germinated in the greenhouse. The results obtained include a karyotype analysis of mitotic chromosomes, a discussion of meiosis, a discussion of B-chromosomes, and a series of photographs depicting the stages of mitosis and meiosis in this species.
Fritillaria atropurpurea has a diploid chromosome number of 24, plus from zero to two B-chromosomes. Two pair of chromosomes have median centromeres while the other ten pair have sub-terminal to terminal centromeres. Two pair have secondary constrictions and satellites. The length of the chromosomes in colchicine treated material ranges from 12.64 to 19.11 microns, with a width of 2.50 microns. During meiosis, pairing is about 95% complete, and an average of 2.50 chiasmata are formed per bivalent, with no localization of chiasmata observed. There is negligible terminalization between diplotene and anaphase I. Mitosis in this species is regular
