Euphorbia micractina Boiss.

Euphorbia micractina varies very much in W China. However, its 5-8 involucral leaves and rays, and small gray-brown seeds, with a very shortly stipitate caruncle, easily separate it from otherwise similar species. Euphorbia lancasteriana was based on plants with pendent stems growing in a narrow, shaded gorge. Similar pendent stems have been seen scattered in other areas and are best regarded as just an ecotype.

Herbs, perennial, 20-50 cm tall. Rootstock tuberous or rhizomatous, 10-12 cm, tubers 6-12 mm thick, rhizomes 2-3 mm thick, remains of old stems inconspicuous. Stems in groups up to 4, 1-6 mm thick, more slender below ground, upper parts usually unbranched, often with very slender lateral branches, drying yellowish or purplish, glabrous. Leaves alternate; stipules absent; basal scale-leaves oblong; petiole absent or nearly so; leaf blade narrowly elliptic to ovate-elliptic, 1-3 × 0.5-0.7 cm, both surfaces glabrous, base cuneate or subcuneate, very variable, sometimes almost amplexicaul on lowermost leaves, margin entire, apex obtuse; midrib prominent abaxially, grooved adaxially, lateral veins inconspicuous or invisible. Inflorescence a terminal pseudumbel, usually also with slender, long-pedunculate dichasial cymes from subterminal axils; primary involucral leaves 5-8, similar to normal leaves, margin entire, base ± rounded, apex rounded or cuspidate, primary rays 5-8, 0.5-4 cm; cyathophylls 2 or 3, ovate-rounded, ca. 6 × 4-5 mm, base cuneate, apex rounded. Cyathium subsessile; involucre cup-shaped, ca. 2 × 1.5 mm, glabrous, lobes triangular or linear-triangular, glabrous or sparsely pilose; glands 4, pale yellow-brown, rounded to transversely elliptic, entire. Pilose bracteoles sometimes present. Male flowers many, exserted from involucre. Female flower: ovary exserted from cup, densely tuberculate, glabrous; styles connate for less than 1/4 length, persistent, style arms shortly 2-lobed; style arms slightly enlarged. Capsule globose, ca. 3.5 × 3.5 mm, exserted from involucre, sparsely softly spiny or tuberculate along angles, very variable. Seeds broadly ovoid, ca. 2 × 1.5 mm, gray-brown, smooth, adaxially white striate; caruncle present, peltate, very shortly stipitate. Fl. and fr. Jun-Jul.

Gansu, NW Henan, Ningxia, Qinghai, Shaanxi, Shanxi, Sichuan, E Xinjiang, Xizang [Kashmir, Korea, Pakistan, Russia (Far East)].

Mountain slopes, meadows, sparse forest margins, shaded rock clefts on vertical moist walls of narrow gorges, on sandstone or limestone; 900-2700 m.

Euphorbia lancasteriana Radcliffe-Smith; E. lucorum Ruprecht var. parvifolia H. L. Yang; E. tangutica Prokhanov; E. villifera W. T. Wang (1988), not Scheele (1849); E. wangii Oudejans.