Floral biology of Pterocarpus indicus Willd. (Narra): a distinctive bee pollination syndrome

Escobin, R.P.; Rojo, J.P.

Floral biology of Pterocarpus indicus Willd. (Narra): a distinctive bee pollination syndrome

1996

Escobin, R.P. | Rojo, J.P. (Forest Products Research and Development Inst.- Dept. of Science and Technology, College, Laguna (Philippines))

The floral biology of Pterocarpus indicus Willd (narra) in Mt. Makiling, Luzon, Philippines was studied. Floral morphology was described in relation to the pollination syndrome. The flowers and fruits that fell within the 1 x 1 quadrant laid under the trees were collected, and the total was multiplied with the crown area to obtain the total floral and fruit production. The flowers to fruit ratio and the rate of floral abortion were determined. The insect floral visitors were identified and their importance was determined based on pollen load and number of visits per panicle per hour. Bagging experiments were also conducted to determine the effect of bee pollination on fruit and seed set. P. indicus exhibited a distinctive bee pollination syndrome. The flower was yellow, fragrant and offered both pollen and nectar rewards. It bloomed from Feb to June. It was delicate and the petals were easily blown by the wind. It was zygomorphic and morphologically specialized, each part performing a definite function for pollination success. Floral abortion was high with three percent of the flowers setting fruit. Floral longevity was one to two days. A tripping mechanism involving pressure from the weight of the pollinators as they landed on the wings and keel petals exposed the previously covered and protected staminal column and enabled insect pollinators to extract floral rewards and affect cross pollination. Mature fruits started to fall in July to Dec. Important insect pollinators were medium to large bees that included Apis dorsata Fab., A. cerena Fab., Vespidae-1, Vespidae-2 and Xylocopa sp.

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