Stemona tuberosa Seeds | Stemona
LATIN NAME: Stemona tuberosa
COMMON NAME: Stemona
Plant Profile
Large-flowered stemona is the biggest of the genus, a twining herb that climbs three to five metres through thicket and forest edge from the western Himalaya across southern China into Southeast Asia. It dies back each winter to a cluster of thick, pale tubers and renews itself in spring with ribbed stems and broad, ovate leaves held in whorls. The flowers are the difference from its relatives: they are large, solitary and borne at the leaf axils, with four long, narrow, purple-red tepals that flare backwards and a greenish centre. They open in summer and are pollinated by flies attracted to the colour and the faint smell. The plant is common in hill country and is dug for its roots wherever it grows.
Science & Biotechnology
Stemona tuberosa is one of the three species admitted to the Chinese pharmacopoeia as Bai Bu, along with S. japonica and S. sessilifolia, and chemical surveys show that each has a slightly different alkaloid profile. The tuberostemonine group dominates in this species, and it is the group most studied for antitussive activity, with several animal studies showing suppression of cough reflexes at doses that do not sedate. Work on the plant’s insecticidal action has found activity against mosquito larvae and stored-product beetles, and the alkaloids appear to act on insect nervous tissue rather than on the gut. The genus is also unusual in its seed anatomy, with an aril that attracts ants, which carry the seed into nests and thereby disperse it. Wild collection for the drug trade is heavy and mostly unregulated.
Uses & Benefits
The tuber is sliced and dried and sold in Chinese pharmacies for coughs, bronchitis and tuberculosis, usually in compound formulae with other herbs. It is also used externally, as a wash or a poultice, against lice and skin parasites, a use that goes back to the earliest herbals. In the garden the vine is grown for its large, strange flowers and its whorled foliage, on a trellis in half shade where the soil stays moist. It is a good subject for a woodland garden in a mild climate, and it dies down politely in winter. The raw tuber is toxic and should never be chewed; the processed drug is a pharmacy item, not a kitchen one. The plant has no food value.
Growing from Seed
Sow fresh seed in a light mix of leaf mould, sand and compost, pressing it into the surface and covering with a bare millimetre of grit, since light improves germination. Keep at twenty-two to twenty-five degrees with high humidity and shade from direct sun. Germination takes four to eight weeks. The seedling is small and slow, and the first tuber forms late in the first season, so leave it in its pot until the second spring. Grow on in half shade, water steadily, and give it a small trellis at once. Plant out into humus-rich, well-drained soil with leaf litter mulch. Mark the site, because the plant disappears completely in winter.
Our Take
A bigger, bolder stemona with solitary purple flowers and a tuber that pharmacy wants. Half shade and a sturdy trellis.
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