Author: Jan Scholten
English: Langsat; Duku; Doekoe; Dookoo.
Region: E. Asia, Thailand, Malaysia, Indonesia.
Content: lansium acid, arrests heartbeat in frogs; seed unnamed alkaloid and two bitter, toxic principles.
Habitat: ultra-tropical; rainforests; humid river valleys; on limestone; at elevations up to 110 metres; lowland forest; humid atmosphere, plenty of moisture, intolerant of long dry seasons; older plants can tolerate full sun, though some shade is still beneficial; slightly acid, humus-rich, well-drained, fertile soil; dislikes heavy soils.
Culture: productive tree averages 1,000 fruits per year in half shade.
Use: fruit peel and the bark for arrow poison; fruit for food, fresh, candied, preserved in syrup, as dessert, cooked; reforestation of hilly areas; dried peel for the aromatic smoke serving as a mosquito repellent and as incense in the rooms of sick people; wood tar for blackening teeth; wood for house posts, rafters, tool handles, small utensils.
Evergreen, slow-growing tree; 10 to 30 metres tall; only 5 - 10 metres in cultivation; robust, broad-topped, densely foliaged.
Inflorecence: clusters of 2 to 30.
Stem: straight, cylindrical; irregularly fluted; 75cm in diameter; steep buttresses, up to 2 metres wide at the base; unbranched for the majority of the tree; wood is light-brown, medium-hard, fine-grained, tough, elastic, durable, weighing 840 kg m3.
Leaves: conspicuously-veined leaflets.
Fruits: oblong-ovoid or ellipsoid; thin, brownish skin; faintly aromatic; little or no milky latex; short spikes; sweet, aromatic, juicy, subacid; has 5 or 6 segments of aromatic, white, translucent, juicy flesh, with 1 to 3 relatively large and very bitter seeds; low on vitamin C.