Rheum palmatum Seeds | Chinese Rhubarb Herb Officinale Da-huang
LATIN NAME: Rheum palmatum
COMMON NAME: Chinese Rhubarb
Plant Profile
Chinese rhubarb is a large herbaceous perennial, 1.5-2.5 m in flower, with huge, deeply lobed leaves and thick red-based petioles. The root is the medicinal part, and it is one of the oldest traded drugs in the world, moving along the Silk Road long before it was grown in Europe.
The plant forms a massive crown that can be a metre across, and the flower stems rise well above the foliage in summer, carrying panicles of small greenish-red flowers. The leaves die back in autumn and the crown rests through winter.
Rheum palmatum comes from the mountains of western China and Tibet, where it grows in moist, deep soil at altitude. The garden rhubarb of kitchens is a different species, Rheum rhabarbarum, and the two should not be confused in the kitchen or in medicine.
Science & Biotechnology
The root contains anthraquinones, chiefly emodin, rhein and chrysophanol, along with tannins and stilbenes. The anthraquinones are stimulant laxatives, and the tannins are astringent, which is why the same root has been used for both constipation and diarrhoea depending on the dose and the preparation.
Emodin and rhein have been studied for anti-inflammatory and antiviral activity in vitro, and the root is one of the most researched Chinese herbs in western pharmacology. The laxative effect, though, is the well-established one, and it is strong.
The plant also accumulates oxalates, particularly in the leaves, which are not edible. Long-term use of anthraquinone laxatives causes dependence and electrolyte loss, and the root should not be taken continuously.
Uses & Benefits
The root is used in Chinese formulas for constipation, for heat-related conditions and, in small doses, as a digestive bitter. It is also used in some western herbal practice, and it appears in veterinary medicine.
In the garden the plant is a bold architectural specimen for a large border or a damp corner, grown for its foliage and its height rather than for the table. Commercially the root is a traded herb, and the seed is sold to growers who want to produce their own material. It is not a substitute for garden rhubarb.
Growing from Seed
Sow in autumn or stratify for eight weeks at 3-5°C, then sow 1 cm deep at 15-18°C. Germination is slow and uneven, and the seedlings are small in their first year. Fresh seed gives the best results.
Plant out in full sun or light shade in deep, moist soil, with plenty of compost. Water well through the first two summers; the plant resents drought. Allow 1 m per plant, since the crown spreads. Lift and divide every five or six years, and remove the flower stems if the foliage is the point. In a small garden, sink a large container into the ground to contain the crown, since the plant spreads steadily once settled.
Our Take
A dramatic foliage plant with a serious medicinal history, best grown for its leaves and left out of the kitchen.
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