FLORAL BIOLOGY AND POLLINATION IN VITEX MISSIMA (VERBENACEAE)

摘要

V. altissima is a deciduous tree species and blooms during June-July. The flora! characteristics such as purple flowers, no perceptible smell, tubular corolla, and non-exposed nectar deposited at the bottom of the corolla tube strongly select the visitors and pollinators, demanding a more elaborated intrafloral behaviour. The lower elaborate lower lip of the corolla provides comfortable landing place for the foragers. Since the anthers dehisce during mature bud stage, the newly open flowers offer both nectar and pollen readily to the foragers. The nectar is hexose-rich and sugar concentration ranges from 24-28%. Nymphalid and Lycaenid butterflies and bees pollinate the flowers. Although bees effect pollination, they reduce the availajjility of pollen for pollination. Therefore, V. altissima is primarily psychophilous while melittophily is an additional pollination mode. The Scarabaeid, Popillia impressipyga acts as Bud and flower predator; its feeding affects the reproductive success of the plant.The calyx in fertilized flowers gradually enlarges and acts as fruiting calyx to harbour the growing seeds. The seeds mature within six weeks and fall off to the ground due to gradual wrinkling of the drying calyx from the base to the top. Since seeds are light in weight, high winds disperse them to other places when dry conditions exist due to dry spell that usually occurs during rainy season.