Dillenia suffruticosa (Griff.) Martelli, locally called simpoh air, is the common Dillenia found in wet places in Peninsular Malaysia. Suffruticosa in Latin means somewhat woody, which draws attention to its shrubby habit because most Dillenia species are trees (Hoogland, 1954). It is a pioneer species and grows vigorously on eroded soil, wasteland, and forest margins or in swampy areas. Simpoh air is so-called locally because it commonly grows in wet places. There are 10 species of Dillenia in Peninsular Malaysia (Tan & Latiff, 2014).

This shrubby plant can grow up to 10 m tall and has beautiful large glossy leaves (ca. 15–25 by 8–12 cm) with conspicuous veins, large yellow flowers (ca. 8–11 cm diam.), and pink star-shaped mature fruits.

The fruit is surrounded by thick red sepals and when ripe splits open into a pretty pink star-shaped structure exposing the seeds which are covered by a fleshy red aril. The seeds are attached to the margin of the sepals but are rarely seen because they are eagerly eaten by birds. The difference between the similar looking flower and fruit buds is that the flower bud faces downwards while the fruit bud faces upwards. An interesting feature of this plant is that if you put your ear close to the trunk or branch you can hear it hiss when cut.

Simpoh air has very deep tap roots to reach underground water sources. So village elders usually use this tree as a guide as to where to dig a well. In times past, the leaf was used to treat bleeding wounds. Today its large leaf is still used to wrap food, such as tempe, fermented soybean cakes. Nowadays, it is planted as an ornamental along roadsides because it blooms continuously and is easily planted using seeds. It is the national flower of Brunei.