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Zi Cao (Lithospermum erythrorhizon)

By June 30, 2010October 29th, 2019No Comments

Zi Cao

Botanical name: Lithospermum erythrorhizon
Common name: Lithospermum, Groomwell root
Literal name translation: purple herb

Family: Boraginaceae, borage family
Part used in Chinese medicine:  root

Major Chinese medicine actions:
Clears heat, cools blood, resolves toxin

Zi Cao

Zi Cao
Photo Credits: (top to bottom)
Photo 1: Lithospermum erythrorhizon; 06/2008; author C. Micleu; permission Jade Institute
Photo 2: Lithospermum erythrorhizon; 06/2008; author C. Micleu; permission Jade Institute


Lithospermum erythrorhizon is native to Eastern China, Japan and Korea, growing in woodland edges and on the grassy slopes of mountains and hills. The roots are a deep purple color and are also cultivated in Japan as a dye plant.

Growing and Propagation

The plant requires a sunny location, but can be grown in part shade, and prefers moderately fertile, moist, but well-drained soil. It grows vigorously to 18-24 inches high, producing many small white flowers from June to September, then small hard nutlets in the fall. The plant is hardy to USDA zones 4 or 5.

Easily propagated by seed, it can be sown in spring or autumn in a cold frame, then planted in a permanent location in late spring or early summer after the last frost. It can also be grown from cuttings or division made in autumn.

Harvesting and Preparation

The roots can be harvested in autumn after 3 or 4 years of growth. For medicinal use, the best quality roots are slightly soft and have a purple-red colored cross section. The yellowish white center of the root should be very small.

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