The tree can grow up to 30 m in height with an umbrella-shaped crown, spreading 20 to 30m across. The bark is dark brown, rough and flaky in mature specimens while its leaves are twice pinnate compound. Its small clusters of flowers are pinkish or whitish and slightly fragrant and its fruit pods are thick, long, straight and fleshy inside. The pods ripen black and do not split open. The seeds readily germinate into seedlings, sometimes while still inside the fruit. Epiphytes like ferns and orchids tend to perch on old Rain Trees.
The leaflets of the Rain Tree fold up in the evenings; this was why the Malays called it Pukul Lima, which means 5 o'clock. This was because 5 pm used to be closer to the sunset hour in Singapore and Malaysia before changes to Standard Time were made on 1 Jan 1982. Notably, the leaflets began to close about one-and-a-half hours before sunset and open about the same time after sunrise. The leaflets also close during the day when the sky was overcast, thus giving rise to the name, Rain Tree.
This Tropical American species has been dispersed throughout the tropics since the middle of the 1900s. It was introduced to Singapore in 1876 and spread throughout the region. Due to its excellent shade, the species was planted in the 1900s in coffee and nutmeg plantations, and along roadsides. The sweetish fruit pulp was relished by cattle, goats, horses, pigs and even children in some countries.
This is one of the tallest Rain Tree in Singapore at 35 m and it was endorsed as a Heritage Tree in 2015.