Cytogenetics and cytotaxonomy ofVelloziaceae

Chromosome number and other cytological features are reported from 35 species ofVelloziaceae, including several African and Brazilian populations. All analyzed species show areticulate interphase nuclei and prophase/prometaphase chromosomes with proximal early condensation. Most heteropycnotic blocks do not seem to correspond to heterochromatin since, at least inVellozia patens, they do not stain differentially after C-banding procedures. Regarding the chromosome number, three main groups could be identified. The first comprised diploid species of the generaNanuza, Vellozia and the Brazilian species ofXerophyta with 2n = 14 or 16; the second comprised tetraploid species with 2n = 34, and included all Brazilian species of subfam.Barbacenioideae; the third group, of hexaploid species, comprised the African representatives of the genusXerophyta. A single population ofVellozia, possibly of hybrid origin, had 2n 32. A basic number of x = 8 is proposed for the family. The karyological information supports the hypothesis that theVelloziaceae originated on the South American, rather than on the African continent.