118. Euphorbia serrata Linnaeus, Sp. Pl. 1: 459. 1753.
Saw-toothed or toothed or serrate spurge Saw-toothed or toothed or serrate spurge
Galarhoeus serratus (Linnaeus) Haworth; Tithymalus serratus (Linnaeus) Hill
Herbs, perennial, with thick rootstock. Stems erect, branched, 10–70 cm, glabrous. Leaves: petiole absent; blade lanceolate, ovate-lanceolate, linear, or linear-lanceolate, 10–70 × 2–20 mm, base acute or obtuse, margins irregularly serrate, apex acute to obtuse, surfaces glabrous; venation inconspicuous, only midvein prominent. Cyathial arrangement: terminal pleiochasial branches 3–5, each 1–3 times 2-branched; pleiochasial bracts ovate-lanceolate, usually shorter and wider than distal leaves; dichasial bracts distinct, ovate or deltate, base obtuse to cordate, margins irregularly dentate, apex acute, or obtuse, mucronate; axillary cymose branches 0–3. Cyathia: peduncle 1–5 mm. Involucre campanulate, 2–4 × 1.2–3 mm, glabrous; glands 4–5, elliptic, ovate, or suborbiculate, 1.2–1.8 × 1.5–2.7 mm; horns absent or slightly divergent, 0–0.6 mm. Staminate flowers 20–40. Pistillate flowers: ovary glabrous; styles 1–2 mm, 2-fid. Capsules subovoid, 4.5–6 × 4–5 mm, 3-lobed; cocci rounded, smooth occasionally slightly puncticulate, glabrous; columella 4–4.5 mm. Seeds grayish, cylindric, 2.5–3.1 × 1.7–2 mm, smooth or slightly dotted; caruncle subconic, lobed, 1–1.5 × 0.5–1 mm.
Flowering and fruiting spring–fall. Waste places, disturbed sites, roadsides, fields, pastures; 0–300 m; introduced; Calif.; Europe; Atlantic Islands (Macaronesia).
Euphorbia serrata, native to the western Mediterranean region of Europe and Macaronesia, is listed as a noxious weed by the state of California. In the flora area, it has been found in coastal counties from Sonoma to Monterey counties; attempts to eradicate it may have been successful.