The Barnadesioideae are a basal subfamily of Asteraceae comprising ca. 90 species in 9 genera. It is an entirely South American group with a characteristic floral indumentum and (in most) pseudobilabiate corollas and paired axillary spines. Apart from the obvious relevance of the group for determining the origin and relationships of Asteraceae, the Barnadesioideae show interesting biogeographical patterns with apparently recent radiations in the northern Andes from an area of origin in the southern part of the continent. Phylogenetic analyses of the group based on morphological data have given conflicting results, making biogeographic interpretations difficult (cf. Bremer 1994 and Stuessy 1996). Sequences of the trnL intron show limited infrageneric variation, but indicate a close relationship between the woody genus Barnadesia and the subacaulescent herb Huarpea, a relationship also supported by pollen morphology. Most species of Barnadesia occur at high altitudes in the northern Andes, which may reflect a recent radiation from a southern Brazilian or northern Argentinian area of origin. Doniophyton comprises two species of annuals and is derived from within the shrubby genus Chuquiraga, a relationship also supported by anther morphology. Both genera are widespread in the southern Andes and Patagonia, one section of Chuquiraga also being represented in the northern high Andes. A third case of northern Andean radiation is found within the genus Dasyphyllum which is sister to the aforementioned clades. A study of nuclear ribosomal ITS variation is under way, with the aim to further resolve the phylogeny of the Barnadesioideae and reconstruct their biogeographic history in greater detail. This research is supported by The Lewis B. and Dorothy Cullman Foundation.

Key words: Andes, Asteraceae, Barnadedioideae, biogeography, molecular systematics