Pollination ecology of Brownlowia tersa (Malvaceae), a Near Threatened non-viviparous true mangrove shrub

Abstract

Brownlowia tersa is a low-ground semi-evergreen shrub species. The phenological events occur sequentially—leaf fall, leaf flushing, flowering and fruiting from April to November. It is hermaphroditic, protandrous, self-compatible, facultative xenogamous, and melittophilous involving worker honey bees, small male and female carpenter bees and male and female cuckoo bees. Of these, worker honey bees and female carpenter bees forage for both pollen and nectar while male carpenter bees and both sexes of cuckoo bees forage exclusively for nectar. Cuckoo bees are very important for cross-pollination because they are swift fliers and visit many flowers from different plants in the shortest time. Carpenter bees and honey bees are largely important for self-pollination as they are not fast fliers and tend to spend more time at each flower for forage collection. The flowers have a specialized pollination mechanism to resort to autonomous autogamy if not pollinated but this mode of pollination is subject to the availability of pollen in its own anthers. Fruit is a 1-seeded follicle produced from a single carpel of the flower. It is indehiscent and floats in tidal water when detached from the plant. When settled in muddy substratum, it breaks open to expose the seed which germinates and produces a new plant in quick succession. The study reports that the plant is highly threatened due to different human economic activities taking place in the area and hence immediate in situ conservation measures are required for its protection and propagation.