The Reproductive Ecology of Canavalia rosea (Fabaceae) on Anak Krakatau, Indonesia

Abstract

Pioneer plant species are expected to have higher fruit-to-flower ratios than plants found in more established habitats. This was not found to be the case with Canavalia rosea on Anak Krakatau, Indonesia. Canavalia rosea is a pantropical pioneer plant species of beach habitats. On Anak Krakatau fruit-set in C. rosea in July 1992 ranged between 10 and 19% and a study of pollination and resource levels was undertaken to determine the cause of low fruit-to-flower ratios. An examination of flowering and fruiting phenology, breeding system and floral visitors revealed that low fruit-set in the population could not be explained by either a lack of pollinators or low levels of deposited pollen. Experimental removal of pods resulted in a near five-fold increase in fruit-set on subsequent flowers on treated plants compared with natural levels, indicating that fruit-set was resource limited. Low fruit-to-flower ratios do not detract from the colonising success of this species however, because individual plants flower prolifically year-round ensuring a constant production of propagules.