Estudios cariológicos en Asteraceae. VIII

Abstract

Meiotic and/or mitotic chromosome numbers were determined and observations on meiotic behavior were made in 14 accessions belonging to 14 especies concerning 8 genera distributed in 4 tribes of the Asteraceae. Five species are investigated chromosomally for the first time. These are as follows, tribe Mutisieae: Brachyclados cespitosus (Phil.) Speg. (n = 23), Nassauvia pygmaea (Cass.) Hooker (n = 22); tribe Cichorieae: Hypochoeris acaulis (Remy) Britton (n = 4,2 n= 8), Hieracium glaucifolium Poepp. ex Froelich in DC. (2n = 18) and Hieracium aff. palezieuxii Zahn (2n = 18). Different chromosome number to those previously reported in the literature were found for Hypochoeris chondrilloides (A. Gray) Cabrera (n = 8), Baccharis ulicina Hook. Am. (2n = 18+3B), Conyza aff. bonariensis (L.) Cronquist (2n = 18). The karyotypes of Brachyclados lycioides Don, Hypochoeris acaulis (Rerny) Britton, Hieracium aff. palezieuxii Zahn and Senecio chilensis Less. are described for the first time. Meanwhile, the karyotypes of Hypochoeris microcephala (Sch. Bip.) Cabrera var. albiflora (Kuntze) Cabrera, H. chillensis (Kunth) Hieron and H. megapotamica Cabrera showed to be slightly different with those described in previous publications. The significance of some of the results in relation to taxonomical and evolutionary problems is discussed.