Senecio L. (Asteraceae) in Australia: Reproductive biology of a genus found primarily in unstable environments

Abstract

The reproductive biology of 28 native and four exotic species of Senecio is described in terms of their breeding system, longevity, habitat stability, seed size and number, dispersal potential and seedling establishment. Nineteen species (15 perennial, 2 annual, 2 ephemeral) are self-incompatible, 13 are self-compatible (4 perennial, 7 annual, 2 ephemeral) and nearly all occur in unstable environments. The success of the perennial species in unstable environments perhaps reflects the fact that they all reach sexual maturity within 1 year of germination and, provided populations of self-incompatible species are large enough, they can set seed in the first year.