Scaphium affine Seeds | (sterculia Lychnophora)
LATIN NAME: Scaphium affine
COMMON NAME: Malva Nut
Plant Profile
Scaphium affine is the malva nut tree of Southeast Asia, whose seeds swell into a jelly that is drunk across the region for sore throats. It grows in the lowland and hill forests of Thailand, Cambodia, Vietnam, Malaysia and Indonesia, on deep, moist soils in valleys and along rivers, where it becomes one of the tallest trees in the forest. It reaches twenty-five to forty metres, with a straight, buttressed trunk and large, leathery leaves. The fruit is a cluster of five woody follicles that split to release a single seed with a long, papery wing, and the seed kernel is the part that is used: dropped into water, it swells into a translucent mucilage several times its size. In Vietnam the drink is sold on street corners in summer, and in Malaysia the swollen seeds are eaten as a dessert. The timber is light and soft and is used for boxes and matches.
Science & Biotechnology
Scaphium affine belongs to the mallow family, in the group formerly treated as Sterculiaceae, and its seed is unusual in storing a large reserve of mucilage in the outer cells of the kernel. The mucilage is a polysaccharide that absorbs many times its weight in water, forming a bland, slightly sweet gel, and it is this that makes the seed valuable in drinks and in medicine for throat irritation. The tree is a tall emergent of the dipterocarp forest, and its winged seed is dispersed by wind, spinning away from the parent in the way of a maple key. It flowers irregularly, and good fruiting years are separated by several poor ones, which makes the crop unpredictable for collectors. The species is harvested from wild trees rather than plantations, and although it is not yet threatened, the trade depends on a forest that is being cleared. Its timber is used locally but is not durable.
Uses & Benefits
The seed is the commercial product: it is sold dried in markets and used to make a cooling drink, often with sugar and lime, and it is a traditional remedy for sore throat, cough and constipation in Vietnamese, Thai and Chinese medicine. In Malaysia and Indonesia the swollen seeds are eaten as a dessert with syrup, and the mucilage is used to thicken soups. The wood is light, soft and easy to work, and it is used for boxes, matches, plywood and temporary construction, though it rots quickly. The tree is sometimes planted as a shade tree and in reforestation, and its large seed crop is eaten by squirrels and birds. For a gardener in the tropics it is a giant forest tree rather than a garden plant, and it needs deep soil and room. The seed sold for drinks should be bought from a reputable source, since it is collected from the wild.
Growing from Seed
Sow the winged seed fresh, laid flat on the surface of a moist, free-draining mix at 25 to 30 degrees, and cover it lightly; germination takes two to six weeks. The seedling develops a long taproot, so use a deep container and plant out while it is small. Grow it in bright shade for the first year, then in full sun. Choose a site with deep, moist, well-drained soil and plenty of room, since the tree becomes enormous. Water through the first two dry seasons and mulch widely. The tree is tender below about ten degrees, so it is suitable only for the humid tropics. Protect the young trunk from browsing animals, and do not prune the leader. It is fast growing once established but slow to flower, and fruiting is irregular.
Our Take
A giant Southeast Asian forest tree whose winged seed swells into a cooling jelly. One for the tropics, not the garden.
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