Arnebia euchroma (Royle) I. M. Johnst.

The species is variable throughout its distributional range. The variation pattern (in size of plant, glandulosity, leaf breadth, infloressence and flower size) depends on the breeding behaviour due to heterostyly ensuring outcrossing. The ssp. grandis (Royle) I. M. Johnston from Iran differs mainly from the type subspecies in the cauline leaves with leaf base distinctly subcordate. The root exudes a purplish dye. Found from 3300-4800 m in the Himalaya.

The roots are used medicinally.

An erect hairy perennial. Roots thick, exuding a purplish dye. Stems several, up to 40 cm tall, axillary, arising amidst the leaves of previous year, fistular, striate, strigosely hairy: hairs up to 2 mm long. Basal leaves 3.5-12.5 x 5-11 mm, upper ones shorter, lanceolate, strigosely hairy, the hairs with bulbous base; nerves impressed above, prominent on the under surface. Inflorescence ± globose, 4-5 cm broad. Bracts leafy, ± size of calyx. Flowers yellow to purple in colour, sessile to subsessile, heterostylous calyx 13-17 (-25) mm long, villous with yellowish-white to white hairs up to 2 mm long; lobes linear-lanceolate,. Corolla tube 9-17 mm long, limb 10-15 mm broad; lobes suborbicular. Anthers linear, 2.4-3 mm long, attached near throat of corolla tube or at the middle. short styles 8 mm long (long styles 12.5 mm) reaching middle of corolla tube, bifid at apex. Stigmas 2, obtuse. Nutlets ± 3.5 mm long, rugose-tuberculate, greyish in colour, keeled.

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.

W. & C. Asia, Himalaya (Kashmir to Nepal), Tibet.

Distribution: Iran, Afghanistan, Pakistan from Kashmir eastward to Nepal.

3500-4000 m

Fl. Per.: June-July.

Rocky slopes, gravelly marshes, meadows. Xinjiang, W Xizang [Afghanistan, NW India, Kazakhstan, Kyrgyzstan, Nepal, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia]

Lithospermum euchromon Royle, Ill. Bot. Himal. Mts. 1: 305. 1839; Macrotomia euchroma (Royle) Paulsen.

Arnebia euchroma là loài thực vật có hoa trong họ Mồ hôi. Loài này được (Royle) I.M.Johnst. mô tả khoa học đầu tiên năm 1924.

软紫草（学名：Arnebia euchroma）为紫草科假紫草属的植物。分布在印度、阿富汗、克什米尔、巴基斯坦、尼泊尔、伊朗、俄罗斯以及中国大陆的西藏、新疆等地，生长于海拔2,500米至4,200米的地区，多生在草地、砾石山坡、洪积扇和草甸，目前尚未由人工引种栽培。