Germination ecology of three Asteraceae annuals Arctotis hirsuta, Oncosiphon suffruticosum, and Cotula duckittiae in the winter-rainfall region of South Africa: A review

Abstract

Asteraceae annuals from South Africa’s winter-rainfall region often exhibit poor germination, and it is a challenge to establish a garden display using fresh seeds from the wild. Arctotis hirsuta (Harv.) Beauvard is a popular ornamental, Oncosiphon suffruticosum (L. Bolus) K. Bremer & Humphries is important in traditional medicine, and Cotula duckittiae (L. Bolus) K. Bremer & Humphries has a vulnerable (VU) status on the red list of South African plants. C. duckittiae is teetering on the brink of extinction in a few localities on severely threatened ecosystems due to continued pressure on land for housing developments and invasive aliens. At present, there is no knowledge of O. suffruticosum being cultivated exclusively for its healing properties. The successful cultivation of this species may allow it to fulfil not only a more acute medicinal role in society but also in the economy to create precious job opportunities. The potential to develop or improve certain plant breeding lines of A. hirsuta commercially, besides just normal wild forms of these species at the Kirstenbosch National Botanical Garden, is huge. This, in addition to the ongoing pressure exerted on wild populations of C. duckittiae, warrants investigations into aspects of germination ecology of this VU species of the West Coast.

Keywords

• african asteraceae
• extinction
• red-listed plants
• seed dispersal
• sowing depth