Gypsela anatomy in the 'Cotuleae' (Asteraceae–Anthemideae)

Ontogeny in Cotula australis, Leptinella dioica and L.pyrethrifolia confirms the presence of layers derived from the endosperm, testa and pericarp surrounding the embryo in mature cypselae in Asteraceae. The structure of mature cypselae of 24 species, representing all 12 genera that have been assigned to the 'Cotuleae', is reported. Several characters that appear to be relatively constant within genera or groups of genera are identified as providing information on affinities above the generic level. The data support the conclusion that the 'Cotuleae' is an unnatural assemblage: Cotula, Leptinella, Nananthea and Soliva appear to form one close-knit group, and Dimorphocoma, Elachanthus and Isoetopsis another, while the remaining genera are highly diverse. The first group appear to be good members of the Anthemideae. Evidence is provided to support the placement of the second group in the Astereae near Minuria. Cypsela characters support the placement of Plagiocheilus near Solenogyne.