Sterculia monosperma Seeds | Chinese Chestnut

Red star-shaped fruit capsules of Chinese Chestnut (Sterculia monosperma) opening to show black seeds — Chinese Chestnut (*Sterculia monosperma*): Malvaceae, the ping po of southern China, grown for its chestnut-like seeds.

LATIN NAME: Sterculia monosperma

COMMON NAME: Chinese Chestnut

Plant Profile

Chinese chestnut, known in Chinese as ping po, is a deciduous tree of the mallow family, native to southern China, Taiwan and Vietnam. It grows five to ten metres with a rounded crown and large, lobed, glossy leaves.

The flowers are small and dull-coloured, but the fruit is striking: a red, star-shaped capsule that splits to reveal black seeds the size of chestnuts. The seeds are edible, and the tree is grown in villages for them rather than for ornament. The trunk is grey and smooth, and the branches spread widely, so an old tree casts a broad patch of shade in summer.

Science & Biotechnology

The species is one of several Sterculia used in Chinese medicine, but it is often confused with Sterculia lychnophora, whose seed is the pang da hai sold for sore throats; ping po is a different species, grown for its edible seed rather than for the throat.

Botanical work has clarified the distinction, and studies of the genus have looked at the mucilage in the seeds and at the red pigments of the fruit wall. Its pollination has also been examined, since the flowers are small and dull and appear to be visited by flies rather than by bees.

Uses & Benefits

The seeds are eaten roasted or boiled, and they taste like chestnuts, which gives the tree its English name. In southern China it is grown in villages and gardens for the seed and for shade, and the bark fibre is used for rope.

The red capsules are ornamental, and the tree is sometimes planted as a curiosity in tropical and subtropical gardens. The wood is soft and used for light construction and for the making of matches and paper.

In Hong Kong and Guangdong the seeds appear in markets in autumn, boiled and sold in bunches, and the tree is a familiar sight in old villages. Its English name causes confusion with the true chestnut, Castanea, which is unrelated and belongs to a different family.

Growing from Seed

Sow fresh seed in spring at 22-28C, one centimetre deep in a free-draining mix; germination is usually within a month. Seedlings need warmth and partial shade in their first year. The seed loses viability quickly once the black coats dry, so sow it within a few weeks of the capsules opening and keep the pots at 25C in a shaded frame. Young trees need staking for the first two years, because the crown is heavy for the stem.

Plant out in a frost-free climate in deep, fertile soil, and water through the dry season while the tree establishes. Prune only to remove dead wood, since the crown forms naturally and the tree resents hard cutting.

Our Take

A tropical tree with a useful nut and a spectacular fruit, though its flowers are easy to miss. It is worth growing where the climate allows, and worth knowing for the confusion with pang da hai.

Tree Seeds