Gromwell, Redroot aka. Zi Cao (Lithospermum erythrorhizon)

Known by various titles, Lithospermum erythrorhizon— ‘Zi Cao,’ ‘Redroot Gromwell,’ or ‘Murasaki,’ has long been a potent healing agent employed in traditional Chinese medicine. Another crucial function of this plant has been as a dye, as it contains the dye compound shikonin (a chemical relative of the common dye compound alkannin, derived from dyer’s alkanet), which creates a beautiful red-purple pigment. It seems that Lithospermum erythrorhizon has been cultivated for dying high-end fabrics since the Nara period in Japan, from 710-794 CE. Known as waka or usu in its native lands, the purple effect of this dye was often reserved for wealthy or ruling classes. It also has a tradition in staining high-quality paper in both Japan and Korea.The rich hues and the medicinal properties of Zi Cao are found in its striking scarlet roots (the reason for its common name). It is recommended to harvest the root after at least 2-3 years of growth for maximum strength.

The first recorded use of this plant was in the ancient Chinese medical text, The Divine Farmer’s Materia Medica, written around 200-250 CE. Gromwell has been known as a cooling and detoxifying herb, often associated with treatment of skin conditions. Current studies are showing a particularly effective application of Zi Cao against dermatitis, with its anti-inflammatory properties, and potential increase of UV-absorptive qualities. Often the plant is applied as plaster or poultice made from the seeds and root. Some indigenous folks in North America would chew this herb as a cold treatment, or drink a strong tea of it for contraceptive purposes.