| Resumo: |
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.
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