Senna tora Seeds | Jue Ming Zi
LATIN NAME: Senna tora
COMMON NAME: Jue Ming Zi
Plant Profile
Cassia tora is a fast annual herb, 30-90 cm tall, with pinnate leaves and pairs of yellow flowers in the leaf axils, followed by long, slender, four-sided pods that curve upward. The seed inside is the medicinal part, small, hard and dark brown.
The plant is a common weed of roadsides and waste ground across the tropics, and it is grown as a crop in India and China for the seed. It flowers within two months of sowing and sets seed heavily, which is why it spreads so easily.
Senna tora comes from tropical Asia and is now pantropical. In Chinese practice the seed is known as jue ming zi, and it is one of the standard herbs for the eyes and for the bowels, a combination that reflects its traditional use rather than its pharmacology.
Science & Biotechnology
The seed contains anthraquinones, chiefly obtusin, chryso-obtusin and aurantio-obtusin, along with naphthopyrones. The anthraquinones are responsible for the laxative effect, and they are the reason the herb is not for long-term use.
The seed is usually roasted before use, which reduces the laxative effect and is said to direct the action upward, toward the eyes. That processing changes the chemistry: heating degrades some of the anthraquinones and alters the ratio of the remaining compounds.
Cassia tora is easily confused with Senna obtusifolia, and the two are harvested together in some regions. The distinction matters for the herbal trade, and it is one of the cases where a botanical name on a packet is worth checking.
Uses & Benefits
The roasted seed is used in Chinese medicine, usually in formulas, for eye problems and for constipation. It is also used in Ayurveda and in Korean practice. The young leaves are eaten as a vegetable in some regions after cooking.
In the garden the plant is a green manure and a bee plant, and it is sometimes grown as a quick cover crop in the tropics. Commercially the seed is a traded herb, and the plant is a minor source of a yellow dye. It is not a plant for casual self-treatment, given the anthraquinone content.
Growing from Seed
Scarify the seed with sandpaper or soak it in warm water for twelve hours, then sow at 1.5 cm deep at 25-30°C. Germination is fast, five to ten days, and the plant grows away quickly.
Sow direct in full sun, at 30 cm apart, in any soil that drains. The plant tolerates poor ground and drought, and it needs no feeding. Water until established, then leave it. Harvest the pods when they turn brown but before they shatter, and dry the seed thoroughly before storing. In warm climates the plant self-sows so freely that one row supplies the next crop, and seed can be taken from pods dried on the plant.
Our Take
A weed with a long medicinal record, worth growing only as a crop and never as a garden plant. The seed needs roasting before use.
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