The Reproductive Biology of Cyrtandra grandiflora (Gesneriaceae) on Oahu

Abstract

In Cyrtandra grandiflora flowering is correlated with a relatively dry period or with the associated increased sunlight that occurs about 3 months prior to flowering. Fruits are mature about 5 months after flowering. Cyrtandra grandiflora is self-compatible and requires pollination for seed set. Anthesis takes 7 days and exhibits marked protandry. The pollen is viable for the entire 7 days; however, the gynoecia are receptive from the opening of the stigma lobes on the fourth day until senescence. This overlap of sexual maturity in the last 3 days of anthesis allows for animal-mediated autogamy. No pollinator was observed, but a crawling, precinctive pollinator is suggested which results in inbreeding, selfing, or the stimulus for agamospermy. Seed set is prolific, with high germination rates, but seedlings are small and slowgrowing and mortality is high in the field. Cyrtandra grandiflora studied here is shown to have a stable, reproducing population.