Pollination biology of Hemiboea ovalifolia (Gesneriaceae), an endangered herb from Guangxi, China

Although information on the reproductive biology of the endangered plant family Gesneriaceae is well known, the pollination mechanisms of these plants in karst regions are poorly understood. This study demonstrated the flowering phenology, pollinators, and breeding system of Hemiboea ovalifolia in karst regions. Findings revealed that the anthesis of H. ovalifolia often occurred late, during sunset, or early morning, with duration of 2-4 days; there was a certain level of temporal overlap between pollen viability and stigma receptivity; the most effective pollinators were Bombus ignitus and Anthophora zonata. Controlled pollination indicated that these plants were pollen limited and exhibited late-acting inbreeding depression resulting from the seed sets; there were significant differences in fruit sets between open-pollination and self-pollination or cross pollination, and in seed sets between self-pollination and cross-pollination or open-pollination. Despite the co-existence of large numbers of fruit and seed sets, and vegetative propagation in H. ovalifolia, a failure in seedling survival, and long duration to establishing first-year seedlings in natural populations suggests that the species does not easily recover from damage.