Flowering Phenology and Pollination Process of Liparis gigantea (Orchidaceae) in Guangxi, China

Liparis gigantea generally grows in subtropical broad-leaved evergreen forests and blooms during the rainy season with purple flowers. Our study focused on floral phenology and morphology, pollinators and their behavior, and pollination mechanism. Our observations showed that the population flowering period lasted for about 20 days, and the single flowering period was 5–6 days. The rate of artificial self-pollination was 100%, which indicated that L. gigantea was self-compatible. L. gigantea achieved reproduction success by attracting Mycomya sp. (Diptera, Mycetophilidae). There was no significant difference between pollination efficiency both at night and during the day (P_removal = 0.34, P_deposition = 0.55). Data on the functional morphological characteristics of L. gigantea and the pollinators related to pollination showed a high match, with the height and width of the pollination tunnel were 3.10 ± 0.34 and 1.93 ± 0.22 mm, and the height and width of the pollinator’s thorax were 5.84 ± 0.96 and 0.96 ± 0.23 mm. The forefoot of insects could be stretched and bent when visiting flowers, so that they could exactly enter and exit the flower with removing or depositing pollinia. While L. gigantea could be pollinated by Mycomya sp., it could also be self-pollinated with the aid of rain. With the assistance of raindrops, the pollinia of L. gigantea slowly slid to the stigma. And this rain-assisted self-pollination mechanism guaranteed the success of reproduction in L. gigantea, especially in the special habitat and flowering season. The results of our study indicated that L. gigantea had a complex pollination reproduction system for insect and rain pollination.