Chromosome numbers and karyotypes in the Australian Gnaphalieae and Plucheeae (Asteraceae)

Abstract

Chromosome number determinations from 152 collections representing 42 genera and 106 species of the Australian Gnaphalieae and Plucheeae are reported. The chromosome numbers of 75 of these species have not been previously counted or differ from those previously reported for species. Chromosome numbers have been documented for the first time for 14 genera: Argyroglottis (n = 12), Cephalosorus (2n = 24), Decazesia (n = 14), Dielitzia (2n = 26), Eriochlamys (n = 14), Erymophyllum (n = 11 and 14), Gilruthia (n = 13), Leucochrysum (n = 9), Myriocephalus s. str. (n = 14, 2n = 24), Polycalymma s. str. (n = 14), Pterocaulon (n = 10), Pterochaeta (n = 12), Quinetia (2n – 24) and Sondottia (2n = 6). Remaining counts augment and agree with previously reported determinations.

Some problems with generic delimitation and interpretation of chromosome data are outlined.

There is an array of karyotypes within the Australian Gnaphalieae and dysploidy is widespread. Polyploidy has also played an important role in the evolution of some taxa. Evidence suggests that the base number for Australian Gnaphalieae is x = 14. This may be the base number for the entire tribe.