蒿状大戟 hao zhuang da ji

Euphorbia lanceolata Sprengel; Tithymalus dracunculoides (Lamarck) Klotzsch & Garcke.

Herbs, annual or short-lived perennial, 10-40 cm tall. Root terete, single, 30-40 cm × 3-8 mm. Stem sometimes branched basally, 3-7 mm thick, branches ascending. Leaves alternate; stipules absent; petiole absent or nearly so; leaf blade linear-oblong, 1-3 cm × 2.5-4 mm, base truncate or subattenuate below, rounded higher up, margin entire, apex rounded or obtuse; lateral veins few, inconspicuous, at acute angle to midrib. Inflorescence an inconspicuous terminal few-rayed cyathium; primary involucral leaves similar to normal leaves, primary rays ca. 3, robust and ascending, dichotomous; cyathophylls 2, similar to normal leaves. Cyathium sessile; involucre broadly campanulate, 2-3 × 3-5 mm, lobes rounded; glands 4, pale brown, crescent-shaped, apex 2-horned, horns light green. Male flowers many, not exserted from involucre. Female flower: ovary exserted from cup, smooth, glabrous; styles free, persistent; style arms 2-lobed. Fruiting peduncle ca. 3 mm; capsule subglobose, ca. 3.5 × 3.5 mm, smooth or obscurely reticulate, glabrous. Seeds ovoid- terete, ca. 2.5 × 1.5-2 mm, gray or dark gray, adaxially striate; caruncle present, stipitate. Fl. Apr-Jul, fr. May-Aug.

Riverbanks, valleys, roadsides of sandy areas; 400-1900 m. Yunnan (Jinsha Jiang valley) [India, Nepal, Pakistan; N Africa, C and SW Asia, S Europe].

Euphorbia dracunculoides is regarded as a problematic weed of certain crops in Pakistan. The Chinese material belongs to the nominal subspecies, subsp. dracunculoides. A number of other subspecies have been recognized from North Africa.