Passerine bird pollination and seed dispersal in Woodfordia floribunda Salisb. (Lythraceae), a common low altitude woody shrub in the Eastern Ghats forests of India

Abstract

Woodfordia floribunda has ornithophilous flowers suited for pollination by passerine birds. The flowering phase, when the shrub is leafless, and the red nectariferous flowers attract various passerine bird species. The visiting birds probe the flowers legitimately to collect nectar and in so doing, their beaks and foreheads strike against the sex organs effecting pollination. Furthermore, the birds move frequently between different shrubs in search of more nectar and in the process cross-pollination is promoted. Hand-pollination tests indicate that this plant species sets fruit through self and cross-pollination and the same is confirmed by very high natural fruit set rate. Bees and butterflies also visit the flowers for pollen and/or nectar but their role in pollination is almost negligible. The fruit is a capsule, with numerous tiny, light seeds, and is enclosed by a persistent membranous calyx. As the calyx is red, it attracts passerine birds during the fruiting phase. Some passerine birds involved in pollination during the flowering phase are also attracted to the growing fruits and feed on the seeds when the latter are mature and ready for dehiscence. In this way, such birds act as seed dispersers. Therefore, W. floribunda is adapted both for pollination and for seed dispersal by passerine birds.