A revised cytotaxonomy of the genus Tulbaghia (Alliaceae)

Abstract

A revision of Tulbaghia (Alliaceae) has been carried out. The genus includes twentyone species and one variety. On the basis of the different karyotypes, the genus can be subdivided into seven distinct Groups. Some species have poly-ploid forms but no true polyploid species has been found so far. A number of species possess heterochromatic segments which may be either mostly distally or proximally located. The heterochromatic segments of Tulbaghia are cold sensitive and specific fluorochrome staining shows that they are composed mainly of highly repetitive sequences of Guanine-Cytidine nucleotides. The possible evolutionary role of heterochromatin as well as that of the B-chromosomes, present in some species, is briefly discussed. The illustrations include micrographs of the mitotic chromosomes as well as colour photographs of the inflorescence of all the species. The typical habitat of two of the species is also illustrated in colour. © 2000 Taylor & Francis Group, LLC.