Fruit polymorphism in ephemeral species of Namaqualand: VII. Diaspore production of plants cultivated from dimorphic diaspores

The influence of moisture, sowing date and density on the dimorphic diaspore production of two polymorphic species, Dimorphotheca sinuata and Arctotis fastuosa (Asteraceae) of Namaqualand, were examined. In the high moisture treatment plants of D. sinuata cultivated from the disc diaspores produced the most diaspores in total but under moisture stress conditions plants cultivated from the ray diaspores produced the most diaspores. Late-sown disc plants produced less diaspores than early-sown plants. Ray plants were not affected by sowing date. Disc as well as ray plants produced less diaspores per plant with increasing density. Plants cultivated from black and brown diaspores of A. fastuosa did not differ in any of the treatments. They were not influenced by moisture and sowing date, but seed production per plant decreased with increasing density