Sophora xanthantha Seeds | Yellow Sophora
LATIN NAME: Sophora xanthantha
COMMON NAME: Yellow Sophora
Plant Profile
Sophora xanthantha is a shrub of the hot, dry valleys of Yunnan, with grey-green pinnate leaves and spikes of clear yellow pea flowers that open in spring. It grows to two or three metres, with arching stems that root where they touch the ground, and it holds a bank of dry soil better than most shrubs. The pods are constricted between the seeds, like a string of beads, and they ripen in late summer.
The species belongs to a genus that is important in Chinese pharmacy, and it grows in the same kind of habitat as the better-known Sophora alopecuroides, the shrub that supplies the drug kudouzi. It is a legume, with the typical pea flower and pinnate leaf, and it fixes nitrogen through root nodules, which is why it can grow on poor, stony ground.
Science & Biotechnology
The genus is defined by quinolizidine alkaloids, chiefly matrine and oxymatrine, which are bitter, toxic and biologically active. Matrine has been studied for antiviral and anti-inflammatory effects, and oxymatrine appears in Chinese formulations for hepatitis. The alkaloids are concentrated in the seed and in the root, and they are the reason the plants are used as medicine and as insecticide.
The alkaloids are also the reason the plants are dangerous. Matrine at high doses causes nausea, dizziness and, in severe cases, convulsions and liver injury, and the therapeutic margin is narrow. The alkaloid profile of S. xanthantha has been less studied than that of its relatives, which means a decoction made from it is a drug of unknown strength.
Uses & Benefits
In local practice the root and the seed are used for skin complaints and for intestinal worms, and the plant is burned as an insect repellent in some districts. The seed is also used as a wash for head lice, and the whole plant is cut as a green manure.
The shrub is planted for erosion control on dry slopes and as an ornamental for the yellow flowers. It is not a commercial crop, and the medicinal use is local rather than part of the pharmacopoeia. Anyone using it should treat it as a toxic plant rather than as a safe herbal tea.
Growing from Seed
The seed coat is hard, so scarify it with hot water or with sandpaper before sowing. Sow in spring at 20 to 25 degrees, and germination is in two to four weeks. The seedling is fast and can be planted out in its first autumn.
The plant wants full sun, sharp drainage and a lean soil, and it tolerates drought and poor, stony ground. It is hardy to about minus ten, and it resents wet ground and rich soil, which produce soft growth and few flowers. Cut it back after flowering if a compact habit is wanted, since it spreads by arching stems.
Our Take
A tough yellow-flowered legume for a dry bank, and a plant whose alkaloids make it a medicine to be left to the pharmacy.
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