Pongamia pinnata
The pongamia is widely distributed along tropical and subtropical coastlines, particularly across East and South Asia, Australia, and the Pacific Islands. Its fruit has a hard, woody shell that allows it to float on seawater for long periods and disperse over great distances by ocean currents, earning it the alternative name “water-flowed bean.”
The pongamia blooms twice a year, typically from April to May and again from September to November. Its delicate, pale purple flowers cluster densely along racemes, filling the air with a gentle fragrance. When in full bloom, the tree’s cascading blossoms create a lush and elegant scene, offering high ornamental value for both sight and scent.
As a typical component of coastal forests, the pongamia exhibits remarkable resilience to challenging environments. It thrives under conditions of high salinity, drought, and strong coastal winds. Its deep, well-developed root system helps stabilize soil and prevent erosion, playing an important ecological role in maintaining shoreline integrity. In addition, the pongamia possesses nitrogen-fixing capabilities, which improve soil fertility and benefit the growth of surrounding vegetation. These characteristics make it an ideal species for coastal embankments, windbreaks, and restoration plantings in tropical coastal ecosystems.
In Taiwan, the pongamia occurs naturally along the northeastern coast, the Hengchun Peninsula, and the shores of Orchid Island (Lanyu). Because of its graceful tree form and attractive flowers, it is also widely cultivated as an ornamental tree in parks, school campuses, and gardens. At the National Museum of Natural Science, pongamia trees are planted in both the Coral Atoll Area and the Littoral Forest Area of the Botanical Garden, serving as representative examples of sea-dispersed coastal plants. Additional specimens can also be seen in the garden near the Information Building, where they provide shade and seasonal beauty for visitors.