Studies in Crataegus. X. A note on the occurrence of diplospory in Crataegus dissona Sarg. (Maloideae, Rosaceae)

This paper records the occurrence of diplospory for the first time in the genus Crataegus L. (Rosaceae). It occurs in C. dissona Sarg., a scarce triploid (2n = 51) of the Great Lakes – New England region. Proof of diplospory is derived from the somatic chromosome count, frequency of trivalents in metaphase I. and cytological study of embryo sac development. The majority of apomictic Crataegus studied, however, are aposporous.Key words: diplospory, apomixes, parthenogenesis, Rosaceae.