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

Reproductive biology of Ophiopogon xylorrhizus Wang et Tai was studied from 1995 to 1997 in Mengla County of Yunnan Province, Southwest China. The sma ll, white or pale pink flowers with stigmas above anthers appeared from lat e March to early April in the study years, and produced abundant pollen, bu t no nectar. Pollen : ovule ratios were 17 185 2175. Every flower opens onl y once and remains functional for 10 12 h. Pollen remains viable for the sa me period. During anthesis, flowers were visited only by single species of thrips (Taeniothrips sp., Thripidae). No airborne pollen grains were collec ted throughout the blooming season, indicating that flowers are not wind-po llinated. About 28% of stigmas of unopened flowers were found with germinat ed 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 producti on to occur. About 75% of ovules were fertilised and developed into young s eeds, but only 12.5% developed into mature seeds in open pollination treatm ents. The remainder of ovules were aborted or destroyed by insects or anima ls during the long developmental phase from April to December. Individuals of O. xylorrhizus commonly produced a single inflorescence with 2 24 flower s (15.3 + 6.5, n = 33), and 1 43 seeds (12.7 + 6.7, n = 33) during the stud y period. Conservation management for this endangered species is urgently r equired and in situ conservation is probably the best method to conserve th is species.