Chromosome studies on some Asteraceae from South America

Abstract

Mitotic or meiotic chromosome numbers for 42 accessions belonging to 39 species of different genera of Asteraceae were determined. First chromosome counts are reported for one genus (Gymnocoronis), 14 species, and one variety. These are as follows: Solidago chilensis var. megapotamica (2n = 2x = 18), Chromolaena barbacensis (2n = 3x = 30), Chromolaena christieana (2n = 3x = 30), Chromolaena hirsuta (2n = 4x = 40), Chromolaena verbenacea (n = 20 II, 2n = 4x = 40), Disynaphia multicrenulata (2n = 2x = 20), Gymnocoronis spilanthoides var. subcordata (2n = 2x = 20), Mikania thapsoides (2n = 4x = 68), Stevia commixta (2n = 2x = 22), Porophyllum brevifolium (2n = 4x = 44), Viguiera rojasii (2n = 2x = 34), Pterocaulon angustifolium (2n = 2x = 20), Gochnatia haumaniana (2n = 4x = 44), Senecio ostenii (2n = 4x = 40), Senecio pinnatus (2n = 8x = 80), and Lepidaploa amambaia (2n = 2x = 28). Chromosome numbers differing from those reported previously in the literature were found in Campuloclinium macrocephalum (2n = 2x = 20), Melanthera latifolia (2n = 4x = 60), Chrysolaena flexuosa (2n = 2x = 20), and Cyrtocymura cincta (2n = 4x = 40). The relevance of the results is discussed in relation to the available data for each of the analysed taxa. © 2007 The Linnean Society of London.