6. Arnebia euchroma (Royle) I. M. Johnston, Contr. Gray Herb. 73: 49. 1924.
软紫草 ruan zi cao
Lithospermum euchromon Royle, Ill. Bot. Himal. Mts. 1: 305. 1839; Macrotomia euchroma (Royle) Paulsen.
Herbs perennial. Roots stout, to 2 cm in diam., containing copious purple dye. Stems usually 1 or 2, erect, branched above, sheathed with remaining bases of leaves, 15-40 cm tall, spreading white or pale yellow hirsute. Leaves sessile, sparsely semiappressed hirsute. Basal leaves linear to linear-lanceolate, 7-20 × 0.5-1.5 cm, base sheathlike, apex short acuminate; stem leaves lanceolate to linear-lanceolate, smaller without sheathlike base. Cymes terminal, 2-6 cm at anthesis, many flowered; bracts lanceolate. Flowers heterostylous. Calyx lobes linear, 1.2-1.6 cm, to 3 cm in fruit, densely pale yellow hirsute on both sides, apex subacute. Corolla dark purple, sometimes pale yellow and purple-red tinged, tubular-campanulate, glabrous or sparsely short pubescent outside; tube straight, 1-1.4 cm; limb 6-10 mm wide; lobes spreading, ovate. Anthers ca. 2.5 mm. Style apex 2-lobed; stigmas 2, obovate. Nutlets black-brown, broadly ovate, ca. 3.5 × 3 mm, scabrous reticulate lined, with few tubercles, adaxially almost flat, center line prominent, abaxially convex, apex subacute; attachment scar somewhat triangular. Fl. and fr. Jun-Aug.
Rocky slopes, gravelly marshes, meadows. Xinjiang, W Xizang [Afghanistan, NW India, Kazakhstan, Kyrgyzstan, Nepal, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia]
The roots are used medicinally.