POLLINATION BIOLOGY AND RESUPINATION OF IMPATIENS GRANDIS (BALSAMINACEAE): AN ENDEMIC BALSAM OF SOUTHERN WESTERN GHATS

摘要

A study on floral phenology, pollination, breeding system and resupination of Impatiens grandis Heyne ex Wall., an endemic and horticulturally promising balsam of southern Western Ghats has been conducted. It flowers in the night during 0300-0500 h. The flowers are protandrous due to anther dehiscence a day before anthesis. They offer both pollen and nectar to the visitors which include honeybees (40%), hawk moths (30%), butterflies (20%) and flies and ants (10%). Pollen viability test indicated that82% pollen grains are viable on the day of anthesis. Stigma is receptive on the 3rd day of flower-opening. The natural fruit set rate is 30% while fruit set through xenogamy 65%. Thus, it is concluded that the plant is self-incompatible and obligate out-crosser. Its dependence on specialized habitats, fragmentation of populations, narrow environmental niche and reproductive constraints such as self-incompatibility, delayed stigma receptivity, poor fruit set, low percentage of seed germination, poor seedling recruitment, etc. could be the reasons for its narrow distribution and endemism in the Western Ghats.