Ontogenesis and reproductive biology of <i>Glehnia littoralis</i> (Apiaceae), a medicinal and endangered species from China

Abstract Understanding plant growth and reproductive biology provides critical insights into conservation and sustainable utilization of plant resources. Glehnia littoralis, a perennial medicinal herb endemic to coastal sandy habitats, is increasingly threatened by anthropogenic habitat degradation. In this study, we investigated its vegetative growth dynamics, breeding systems, and flower visitors for its conservation and utilization. Vegetative development in the first year progresses through five morphologically distinct stages, following seed germination, spanning from April to October. Anthesis begins in mid-to-late May of the second year. Flowering is characterized by two principal features: asynchronous perianth development among individual flowers but synchronized sexual phases within each umbel. The species exhibits multicyclic protandry among umbels and is andromonoecious. Individual flowers exhibit both protandry and herkogamy, effectively promoting cross-pollination. Field observations confirmed entomophily as the primary pollination mode, with diverse floral visitors significantly enhancing pollination efficiency. Pollen viability experiments indicated that pollen remained viable for up to 4 days when stored at 4°C. Notably, stigma receptivity was highest when styles diverged to an angle of 90°, which occurred following the complete abscission of the stamens. By clarifying growth patterns, breeding systems, and optimal pollen–stigma interaction windows, this study provides critical insights for cultivation management, in situ and ex situ conservation efforts, and artificial breeding programmes for this ecologically and pharmacologically important species.