Nephelium lappaceum aka Rambutan

Nephelium lappaceum, or rambutan, is an evergreen fruit tree. It belongs to the Sapindaceae family. Its native range runs from southern China to Malesia. It grows in warm, wet tropical forests. Trees occupy the lower and middle layers of these forests. Their habitats include both dry ground and swamps. People grow rambutan for fruit and as an ornamental tree.

Garden trees often reach 13–23 feet (4–7 metres) tall. Wild trees usually reach 30–49 feet (9–15 metres). PFAF gives a larger height of 66 feet (20 metres). Rare wild trees can reach 144 feet (44 metres). The crown spreads out, with gaps between its branches. The trunk grows straight, though some plants remain shrub-like. Leaves grow alternately along the stems and have a pinnate form. Each leaf has three to eleven leaflets. The flowers are small, and bees and other insects pollinate them. Sources describe the species as self-fertile.

The oval fruit grows in clusters and has bright red skin. Long, thin growths cover the skin and give it a hairy look. Inside, pale flesh surrounds a seed. The flesh tastes sweet and contains plenty of juice. People eat it fresh or cook it. It also goes into syrup, jam, and jelly. Some people roast and eat the bitter seeds. Sources also report that seeds may have narcotic effects. The fruit wall contains a toxic saponin linked to poisoning. Edible flesh does not make every part of the fruit safe.

Rambutan grows fast in warm, humid conditions with ample rain. It prefers moist soil and accepts loam or clay. Acid to neutral soils suit it, including very acid soils. It grows in full sun or partial shade. PFAF lists USDA zones 10–12 and describes it as frost-tender. Cold near 41–43°F can cause leaf loss. Young growth suffers severe damage at about 39°F. Rain through the year suits it best. It can withstand a dry season of two to three months.

The spreading crown offers shade in warm gardens and food forests. Leaves, shoots, and fruit walls supply dyes. Seeds yield oil, and the tree supplies useful timber. Local medicine uses leaves, bark, roots, and parts of the fruit. These uses include treatments for fever, diarrhoea, and headaches. They do not establish safety or proven benefit. Fresh seed loses viability quickly and needs prompt sowing. Growers also use layering and grafting. Useful Tropical Plants reports an IUCN Least Concern assessment from 2013.