Morphological data indicates two major clades of the subtribe Gorteriinae (Asteraceae-Arctotideae)

Abstract

The phylogeny of subtribe Gorteriinae (Asteraceae-Arctotideae) is investigated by means of cladistic analysis of morphological characters. Two sister groups are formed, namely a Gorteria clade also containing Hirpicium and Gazania, and a Berkheya clade, which also contains Cullumia, Cuspidia, Didelta and Heterorhachis. The Gorteria clade has strong jackknife support and is diagnosed by four morphological characters (leaves with longitudinally striate hairs, fringed anther apical appendages, pollen of the "Gazania-type", and subulate-ensiform, ascending style sweeping hairs) that are unique within the Asteraceae. The Berkheya clade is moderately supported and diagnosed by two characters without contradiction (spiny leaves, and mamillate, large style sweeping hairs). Hirpicium and Berkheya are paraphyletic, with the other, morphologically more homogeneous genera (Gorteria, and Gazania, Cullumia, Cuspidia, Didelta and Heterorhachis, respectively) nested within them. There is some evidence for a radiation of species of the summer rainfall area of South Africa and tropical Africa and the corresponding species are nested within a grade confined to the Cape Floristic Region. © The Willi Hennig Society 2006.