Reproductive biology of Ophiopogon xylorrhizus (Liliaceae s.l.): an endangered endemic of Yunnan, Southwest China

Abstract

Reproductive biology of Ophiopogon xylorrhizus Wang et Tai was studied from 1995 to 1997 in Mengla County of Yunnan Province, Southwest China. The small, white or pale pink flowers with stigmas above anthers appeared from late March to early April in the study years, and produced abundant pollen, but no nectar. Pollen : ovule ratios were 17 185 ± 2175. Every flower opens only once and remains functional for 10–12 h. Pollen remains viable for the same period. During anthesis, flowers were visited only by single species of thrips (Taeniothrips sp., Thripidae). No airborne pollen grains were collected throughout the blooming season, indicating that flowers are not wind-pollinated. About 28% of stigmas of unopened flowers were found with germinated pollen grains and seed set took place in single flowers that were bagged at the bud stage, which indicated autogamy and autonomous self-pollination. Ovary walls ruptured 4–5 days after fertilisation, allowing seed production to occur. About 75% of ovules were fertilised and developed into young seeds, but only 12.5% developed into mature seeds in open pollination treatments. The remainder of ovules were aborted or destroyed by insects or animals during the long developmental phase from April to December. Individuals of O. xylorrhizus commonly produced a single inflorescence with 2–24 flowers (15.3 ± 6.5, n = 33), and 1–43 seeds (12.7 ± 6.7, n = 33) during the study period. Conservation management for this endangered species is urgently required and in situ conservation is probably the best method to conserve this species.