On the cytotaxonomy of the genus Eriospermum Jacq. ex Willd. (Eriospermaceae)

A cytotaxonomic survey has been carried out on 87 species and 11 subspecies of Eriospermum (Eriospermaceae). The results show that the basic haploid number varies from x=5 to x=10 and that, according to karyotype, the species can be subdivided into eight distinct Groups. The larger number of species belong to Group A with 62 taxa. Group E karyotype, found in nine species, is bimodal and includes three large and either six or seven small chromosomes. Some of the karyotype Groups include species which belong to different taxonomic aggregations. Overall, the direct comparison, between the taxonomic conclusions and those indipendently reached through chromosome analysis, has shown a good although not complete concordance. The very distinct karyotypes of the eight Groups of species of Eriospermum suggest specialized genes assemblages in response to environmental conditions. Further, the existence of certain remarkable characters such as the enations present in several species and the peculiar position of the growing point, mostly underneath the tuber, can be considered as special adaptive features to the generally arid conditions in which most of the species live.