EXPERIMENTAL EVIDENCE OF INSECT POLLINATION IN JUNCACEAE, A PRIMARILY WIND-POLLINATED FAMILY

Premise of research.The rush family (Juncaceae) is most often described as wind pollinated. However, flowers in the family have pollen in tetrads and numerous ovules, both unusual features for anemophilous plants. Here, we investigate evidence for wind and animal pollination in the alpine rush Juncus allioides in Yunnan Province, southwest China.Methodology.Pollen and ovule traits, insect visitors to flowers, and the relative contribution of wind, insect, and self-pollination to seed set were examined over two years in natural populations.Pivotal results.Unlike most Juncaceae, J. allioides appears to be largely insect pollinated. The pollen/ovule ratio of plants in both populations was approximate to approximate to 700. Few pollen grains were transported by wind to sticky slides in close proximity to plants, and the seed set of bagged-and-emasculated flowers was very low. Although J. allioides is capable of self-fertilization, insect exclusion by bagging reduced seed set in comparison with open pollination. Field observations revealed diverse generalist insects, including flies, bees, butterflies, and beetles, visiting flowers.Conclusions.Our results confirm earlier, largely anecdotal reports of insect pollination in Juncaceae and suggest that insects may play a more important role in the pollination biology of some species in the family than is often assumed.