A cytotaxonomic study of some species of Pleione D. Don (Orchidaceae)

Abstract

For taxonomic purposes in the genus Pleione D. Don (Orchidaceae) breeding studies, chromosome numbers, karyotypes and analyses of pollen mother cells have been investigated. In addition to confirming many previous chromosome numbers, new tetraploid, hexaploid and triploid counts establish the existence of a tetraploid taxon (P. speciosa), a hexaploid (P. bulbocodioides) and a triploid hybrid (P.humilis‘Frank Kingdon-Ward’). The karyotypes of the diploid species P. bulbocodioides, P.yunnanensis, P. humilis, P.forrestii and P. hookeriana are distinct, whereas those of P.formosana and P. limprichtii have similar morphology to that of P. bulbocodioides, which was also represented in the polyploid taxa. Karyotype morphology provides evidence to trace the putative parents of P. x confusa and P. humilis‘Frank Kingdon-Ward’. Results from pollen mother cells and karyotype analyses suggest that P.formosana and P. limprichtii are not cytologically differentiated from P. bulbocodiodes, and the taxa P. speciosa, P. limprichtii (tetraploid form) and P. bulbocodioides (6x) are of autopolyploid origin, being derived from the P. bulbocodioides genome. The species limits are discussed.

Autopolyploidy, chromosome number, hybridization, karyotype, pollen mother cell