LOW BASE NUMBERS AND DYSPLOIDY IN ANNUAL HELICHRYSUM MILL. (ASTERACEAE: GNAPHALIEAE)

摘要

We report one new base number for Helichrysum, x = 5, found in the South African species H. indicum (2n = 10), and additional evidence for the recently documented x = 4 found in several South African species: H. litorale ( 2n = 8), H. spiralepis (2n = 8) and H. zwartbergense (2n = 8). Dysploidy is shown as an additional evolutionary trend within the genus, apart from polyploidy which is most extensive and documented. The association of dysploidy processes with the acquisition of an annual life cycle and adaptation to aridity is discussed for these species and other plant groups.