Cytotaxonomic analysis of South American species of Vernonia (Vernonieae: Asteraceae)

Chromosome numbers in 48 populations belonging to 31 species of Vernonia from South America have been determined. First chromosome counts are reported for V propinqua var. canescens (2n = 20), V sceptrum (2n = 80), V rufogrisea (2n = 32), V heringeri (2n = 32), V hovaefolia (2n = 64), V hystricosa (2n = 128), V obtusata (2n = 64), V pseudoincana (2n = 32), V rubricaulis var. australis (2n = 64) and V rugulosa (2n = 30). The basic chromosome numbers x = 10, 14, 15, 16 and 17 were confirmed for New World species of Vernonia. Together with previous records, these numbers suggest that the evolution of Vernonieae has occurred through a combination of polyploidy and aneuploidy. Taxonomic implications of certain counts are also discussed. (C) 2002 The Linnean Society of London.