Zi Cao

Lithospermum erythrorhizon is a perennial herb of the family Boraginaceae native to grassy hillsides and open woodland in China, Korea and Japan. From a thick, woody, deeply purple-red taproot it produces several erect, bristly-hairy stems 40-90 cm tall bearing alternate, sessile, lanceolate to ovate-lanceolate leaves 3-8 cm long with strigose hairs on both surfaces. Small white, salverform flowers about 5-6 mm across with five spreading corolla lobes and a tubular throat are borne in terminal scorpioid cymes from June to August, followed by smooth, shining grey-white ovoid nutlets. The medicinally used root, harvested in autumn, is cylindrical, twisted, 7-14 cm long and 1-2 cm thick, with deeply furrowed purple-red bark that stains the fingers due to its high content of naphthoquinone pigments (shikonin and acetylshikonin).