Sun or summer spurge, wartweed, euphorbe réveille-matin Sun or summer spurge, wartweed, euphorbe réveille-matin

Galarhoeus helioscopius (Linnaeus) Haworth; Tithymalus helioscopius (Linnaeus) Hill

Herbs, annual, with taproot. Stems erect, unbranched or branched, 5–45 cm, usually glabrous or sparsely pilose. Leaves: petiole absent or to 0.5 mm; blade obovate-spatulate, 4–40 × 2–25 mm, base cuneate, attenuate, or auriculate, margins serrulate, apex rounded, surfaces glabrous; venation pinnate, midvein prominent. Cyathial arrangement: terminal pleiochasial branches (3–)5, each 1–2 times 2-branched; pleiochasial bracts obovate, wider than distal leaves; dichasial bracts distinct, obovate or rhombic, ± oblique, base rounded, truncate, or attenuate, margins serrulate, apex rounded; axillary cymose branches 0. Cyathia: peduncle 0.2–1 mm. Involucre cupulate, 1.5–2 × 0.7–1.1 mm, glabrous; glands 4, elliptic, 0.2–0.5 × 0.5–1 mm; horns absent. Staminate flowers 10–15. Pistillate flowers: ovary glabrous; styles 0.7–1 mm, 2-fid. Capsules depressed-globose, 2.5–4 × 3.2–4.2 mm, clearly 3-lobed; cocci rounded, smooth, glabrous; columella 0.9–1.1 mm. Seeds dark brown to blackish, subovoid, 1.6–2.2 × 1.5–1.9 mm, reticulate; caruncle elliptic, 0.9–1.1 × 0.4–0.5 mm.

Flowering and fruiting spring–fall. Roadsides, waste places; 0–1400 m; introduced; Saint Pierre and Miquelon; Alta., B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Sask.; Calif., Conn., Del., D.C., Ga., Idaho, Ill., La., Maine, Md., Mass., Mich., Mont., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., S.C., Tenn., Tex., Vt., Va., Wash., Wis., Wyo.; Europe, Asia, n Africa; introduced also in South America (Argentina, Chile).

Euphorbia helioscopia was collected once in Minnesota in the late 1800s but apparently did not become established there.