Chromosome studies of some Vernonia species (Asteraceae)

chromosomes of 12 vernonia species (asteraceae) from south america were studied. first counts were reported for: v. alpestris gardn. (n = 17), v. chalybaea mart. ex dc. (2n = 32), v. cotoneaster less. (2n = 30), v. fruticulosa mart. ex dc. (n = 16) and v. lithospermifolia hieron. (n = 10, 2n = 20). furthermore, in v. aurea mart. ex dc. (2n = 32), v. mollissima d. don (n = 32) and v. saltensis hieron. (2n = 64) numbers different from those reported in the literature were found. karyotypes were described for some species. v. aurea contains 24m + 8sm chromosomes, v. chalybaea contains 22m + 10sm chromosomes, v. cincta griseb. 36m + 16sm + 8st and v. cotoneaster 18m + 12sm. the basic chromosome numbers x = 10, 14, 15, 16 and 17 were confirmed for south american vernonia species. the results are discussed in relation to previous chromosome studies for the genus.