110. Euphorbia oblongata Grisebach, Spic. Fl. Rumel. 1: 136. 1843.
Egg-leaf or oblong spurge Egg-leaf or oblong spurge
Tithymalus oblongatus (Grisebach) Soják
Herbs, perennial, with woody taproot. Stems erect, unbranched or densely branching, 80 cm, often densely villous (especially young stems and pleiochasial branches). Leaves: petiole absent; blade oblong to narrowly obovate or lanceolate, 15–70 × 6–25 mm, base rounded or truncate, margins finely serrulate, apex obtuse, mucronulate, surfaces glabrous; venation inconspicuously pinnate, midvein prominent. Cyathial arrangement: terminal pleiochasial branches 3–5, each 2–3 times 2–4-branched; pleiochasial bracts ovate, similar in size to distal leaves; dichasial bracts distinct, ovate to suborbiculate, base truncate or rounded, margins entire or finely denticulate, apex obtuse, sometimes mucronulate; axillary cymose branches 0–4. Cyathia: peduncle 1–5 mm. Involucre cupulate to slightly turbinate, 1.5–2.5 × 1.3–1.5 mm, glabrous; glands 2–3, elliptic, 0.6–0.8 × 0.8–1.2 mm; horns absent. Staminate flowers 15–40. Pistillate flowers: ovary glabrous; styles 1.5–2 mm, 2-fid. Capsules globose, 3–4.5 × 3–4.5 mm, slightly 3-lobed; cocci rounded, verrucose-tuberculate, glabrous; columella 2.5–3.3 mm. Seeds brown, ovoid, 2.4–2.6 × 1.3–2 mm, smooth, caruncle reniform, 0.2–0.3 × 0.8–0.9 mm.
Flowering and fruiting spring–fall. Waste areas, disturbed sites, roadsides, fields, pastures; 30–900 m; introduced; Calif., Oreg., Wash.; s Europe.
Euphorbia oblongata is listed as a noxious weed by the states of California, Oregon, and Washington.