Stemona japonica Seeds | Japanese Stemona
LATIN NAME: Stemona japonica
COMMON NAME: Japanese Stemona
Plant Profile
Japanese Stemona is a slender climbing herb of the stemona family, twining weakly through shrubs by means of leaf stalks, with bright-green, heart-shaped leaves and curious, deep-purple flowers that open along the lower stems in early summer, each bloom with six pointed lobes. It dies back each winter to a clustered, tuberous root mass beneath the soil.
That root is the plant’s story: gathered, dried and traded for generations as Bai Bu, a classical Chinese herb. In the garden it is a woodland-edge subject for shaded, leafy, moist ground, scrambling a metre or two through low shrubs or over a small trellis. The flowers hang in short chains from the older stems close to the ground, easily missed until the eye adjusts to their dark purple against the leaf litter.
Science & Biotechnology
The root’s alkaloids, the stemonines, have been the chemists’ interest for a century: they are insecticidal and have been studied both as the basis of traditional preparations and as leads for natural pesticide research.
The plant family is small and relict, and botanists treat it as an ancient lineage; the species features in studies of the family’s classification and of its unusual climbing mechanism, twining by petioles rather than stems. The stemonines’ insecticidal action has been characterised at the molecular level, and the root’s traditional use against lice and other ectoparasites is the folk observation behind that research. The family’s position near the base of the monocot tree has been debated for decades, and each new molecular study has refined, without settling, its exact placement.
Uses & Benefits
In Chinese medicine Bai Bu is a classical herb for stubborn coughs, including whooping cough, and a traditional wash for lice; professional use only. In the garden the deep-purple flowers and leafy stems give a quiet, unusual woodland look.
The thick clustered roots make the plant easy to divide and share once established, and a shaded corner with a small trellis suits it for years without disturbance. Growers who divide the root clusters every few years find the divisions establish quickly, and a single plant can furnish a patch of woodland edge within a season. The plant is also grown by collectors of odd botany, who value the petiole-climbing habit as a living demonstration of how many ways a plant can find to climb.
Growing from Seed
Sow fresh seed on the surface of a loose, humus-rich compost, cover lightly, and keep everything evenly moist in partial shade; dried seed loses vigour quickly, so sow within weeks of harvest.
Grow the seedlings in shaded, humid conditions, pot them on gently, and plant out into leafy, moisture-retentive soil at a woodland edge. The roots are hardy where winters are mild; in cold districts keep it in a pot under cover. In pots, use a deep container and a peat-free, loam-based mix with plenty of leaf mould, and keep the compost from drying completely at any time of year. Keep a small support of twiggy peasticks among the foliage rather than a formal trellis; the plant scrambles more naturally through loose support than it climbs a wire.
Our Take
A slender climber with treasure under the soil and strange purple flowers along the stem. Shade, leaf-mould and steady moisture are its whole contract.
Related Reading
Gardeners who grow Japanese Stemona often pair it with these related subjects: