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.