Pollination Biology of Hemiboea ovalifolia (Gesneriaceae), an Endangered Herb from Guangxi, China

Abstract

Information on the biology of rare species and those with restricted geographical ranges is crucial for predicting their reproductive success, understanding their population dynamics, and suggesting appropriate conservation measures [1][2][3]. As one of the key contributing factors of a species becoming endangered, the plant breeding system has received the most widespread attention and can vary according to species distribution [4]. In general, both the direct and indirect changes in habitat fragmentation can threaten the survival of endangered plants by reducing potential habitat and population viability, or disrupting plant pollinator interactions [1,[5][6]. However, small and isolated plant populations have been one of the problems that scientists have been arguing about for a long time [7-8]. AbstractAlthough 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.