Floral characteristics and butterfly wing pollination of Lycoris aurea

Lycoris aurea is a perennial herbaceous plant with important medicinal and ornamental values in the genus Lycoris Herb, the family Amaryllidaceae. The flower has a spider shape with highly exserted stigmas and anthers, which may represent a unique pollination type. In order to explore this type of pollination, we studied its floral characteristics, breeding system, and floral visitors and their behaviors. The results were as follows:(1)The single flower lasted(5.9±0.1)d and the pollen-ovule ratio(P/O)reached about 23 000. The flowers showed reverse herkogamy. On the beginning of flowering, the style and filaments were separated and the angle between them was about 30°. The style gradually moved towards the filaments in the middle and later stages and were finally on the same line with the stigma 2-3 cm higher than the anthers. The stigmas were receptive throughout the flowering period.(2)The breeding system test was self-compatible and bagged flowers cannot set fruit, indicating that pollinators were necessary for pollen transfer. Supplemental hand pollination significantly increased fruit production, indicating the existence of pollen limitation.(3)Four species of swallowtail butterfly were the effective pollinators. Due to the existence of herkogamy in L. aurea, on the beginning of flowering, their hindwings were likely to come into contact with the flattened anthers. Their hindwings might touch the stigma in the middle and later stages and thus the process of pollen transfer was accomplished. In conclusion, this study shows that the uqique floral characteristics of L. aurea are adapted for butterfly wing pollination and also will lay the foundation for its conservation and sustainable utilization.