乳浆大戟 ru jiang da ji

Euphorbia croizatii Hurusawa; E. cyparissias Linnaeus; E. distincta Stscheglejew; E. eriophylla Karelin & Kirilov; E. esula var. latifolia Ledebour; E. leoncroizatii Oudejans; E. lunulata Bunge; E. maackii Meinshausen; E. mandshurica Maximowicz; E. minxianensis W. T. Wang; E. nakaiana H. Léveillé; E. octoradiata H. Léveillé & Vaniot; E. subcordata C. A. Meyer ex Ledebour; E. takouensis H. Léveillé & Vaniot; E. tarokoensis Hayata; Tithymalus esula (Linnaeus) Hill; T. lunulatus (Bunge) Soják; T. mandshuricus (Maximowicz) Soják; T. subcordatus Klotzsch & Garcke.

Herbs, erect, (15-)30-60 cm tall. Rootstock enlarged or sometimes extensively rhizomatous, brown or dark brown, up to 20 cm × 3-5(-6) mm, branched or not. Stems single or clustered, many branched basally, 3-5 mm thick; sterile stems sometimes present, sometimes overtopping inflorescence. Leaves alternate, often larger toward stem apex; stipules absent; basal scale-leaves few; petiole absent; leaf blade linear to ovate, very variable, (1.5-)2-7 × (0.15-)0.4-0.7(-1.2) cm, base attenuate, cuneate, or truncate, apex acuminate or acute; leaves on sterile branches denser, needlelike, 2-3 × ca. 0.1 cm. Inflorescence a terminal pseudumbel, often with lateral cymes from axils below; cymes mostly dichotomous; primary involucral leaves 3-8, similar to normal leaves to almost orbicular, primary rays 3-8, 2-4(-5) cm; cyathophylls 2, sometimes overlapping at base, usually reniform, occasionally ovate or triangular-ovate, pair often forming complete circle, 0.4-1.2 × 0.4-1 cm, base subtruncate to shallowly cordate, apex shortly acuminate to rounded. Cyathium sessile; involucre campanulate, ca. 3 × 2.5-3 mm, lobes rounded to triangular, tomentose on margin and inside; glands 4, brown, crescent-shaped, usually 2-horned, horns long and acute to short and obtuse or absent, sometimes so tightly incurved that gland looks circular. Bracteoles linear, glabrous. Male flowers many. Female flower: ovary exserted from cup, smooth, glabrous; styles free, persistent; style arms 2-lobed. Capsule trigonous-globose, 5-6 × 5-6 mm, with 3 vertical furrows. Seeds ovoid-globose, 2.5-3 × 2-2.5 mm, yellow-brown; caruncle present, peltate, sessile. Fl. and fr. Apr-Oct. 2n = 40*.

Roadsides, fields, grasslands, steppes, slopes, sparse forests, sandy areas. Throughout China except Guizhou, Hainan, Xizang, Yunnan [Afghanistan, Japan, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Tajikistan, Turkmenistan, Uzbekistan; SW Asia (Iran), Europe; naturalized in North America].

Euphorbia esula is extremely diverse, especially in the form of the leaf blade, involucral leaves, abortive branches, and the horns of the cyathial glands. However, it can be differentiated from E. kansui and E. sieboldiana by the involucre with 5 lobes and 4 glands (and from E. prolifera) and by the involucre without peduncle (from E. latifolia). There are many synonyms from outside China that are not given here. It is classified as a noxious weed in N America.

The seed oil is used in industry.