Studies inCrataegus(Rosaceae, Maloideae). XIX. Breeding behavior in OntarioCrataegusseriesRotundifoliae

摘要

Ontario members ofCrataegusseriesRotundifoliaedisplay breeding behavior that is characteristic of apomictic taxa. Based on a series of analyses, including histological studies of ovule development, chromosome counts, pollen stainability and pollination studies, and phenological analyses, it appears that most of the OntarioRotundifoliaeare tetraploid (2nensp;=ensp;2xensp;=ensp;68), self-fertile, pseudogamous, facultative apomicts. Some triploid (2nensp;=ensp;3xensp;=ensp;51) apomicts are also present inC.dodgeivar.flavida(Sarg.) Smith amp; Phipps. The results presented are congruent with previous studies ofCrataeguscytogenetics. Moreover, these results have assisted the taxonomic analysis of the series by permitting the identification of predominantly apomictic microspecies as well as possible hybrid taxa.