Mixed mating in Banksia media

Abstract

Differential exclusion of vertebrates and invertebrates from the inflorescences of Banksia media R.Br. on the south coast of Western Australia showed the species to be partially self-compatible. Access by invertebrates increased fruit set and additional access by vertebrates resulted in even greater fruit set. Honeyeater birds and marsupial nectarivores were abundant and widespread in the study area and most carried the pollen of Banksia media while it flowered. However, although B. media had the floral characteristics attributed to vertebrate pollination, self-pollination and pollination by insects clearly also play major roles in seed production. Banksia media regenerates solely from seed released after fire and we suggest that its mixed mating strategy is a compromise between inbreeding depression and risk of elimination from areas prone to occasional fires.