Deceptive pollination mechanisms and low natural fruit set in Cymbidium aloifolium (L.) Sw. (Orchidaceae)

Abstract Floral biology and pollination mechanisms of Cymbidium aloifolium an epiphytic orchid were investigated in Tripura, India. The flowering period of C. aloifolium lasted for approximately 4 months from the late spring to the summer, with raceme inflorescence where flowers open acropetally. The flower longevity strictly depends on pollination, 3 to 5 days; otherwise, individual flowers commonly last for one month. The flowers are nectarless, so they have to attract pollinators by the deceptive mechanism for capsule production. Flowers are fully pollinator-dependent as they are self-compatible but cannot autonomously self-pollinate. The Indian honey bee, Apis cerana indica, exclusively pollinated the flowers in the field. Pollinarium attached with the insect's back thorax and head due to their movement through the labellum chamber and pollinated the flower while escaping from the same. Both the studied populations estimate the pollination success but the natural fruit set percentage was very low (13–16%) as the result of a lack of nectar, infrequent flower visits by worker's honey bees, specialized single pollinator, and tight packaging of pollen cap with column of flower.