123. Euphorbia trichotoma Kunth in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 48; 2(qto.): 60. 1817.
Sand-dune spurge Sand-dune spurge
Galarhoeus trichotomus (Kunth) Small; Tithymalus trichotomus (Kunth) Klotzsch & Garcke
Herbs, perennial, with thick rootstock. Stems erect, branched, 15–40 cm, glabrous. Leaves: petiole absent; blade obovate to oblanceolate, 5–20 × 2–7 mm, base broadly attenuate, margins entire, apex acute to obtuse, surfaces glabrous; venation pinnate, very obscure, midvein prominent. Cyathial arrangement: terminal pleiochasial branches 3, each usually 1–2 times 3-branched, sometimes unbranched; pleiochasial bracts similar in shape and size to distal leaves, alternate; dichasial bracts distinct, obovate to oblanceolate, base broadly attenuate, margins entire, apex acute to obtuse; axillary cymose branches 0. Cyathia: peduncle 0.7–1 mm. Involucre hemispheric, 1–1.5 × 1.4–2 mm, glabrous; glands 5, elliptic to slightly crescent-shaped, 0.4–0.6 × 0.9–1.1 mm; horns divergent, 0.1–0.2 mm. Staminate flowers 8–10. Pistillate flowers: ovary glabrous; styles 0.2–0.4 mm, 2-fid. Capsules depressed-ovoid, 1.1–1.5 × 2–3 mm, strongly 3-lobed; cocci rounded, minutely papillate, sometimes appearing smooth, glabrous; columella 1.6–1.9 mm. Seeds white, ovoid-globose, 1.8–2 × 1.6–1.8 mm, smooth; caruncle ± rounded and flattened, 0.3 × 0.3 mm.
Flowering and fruiting year-round (primarily spring–summer). Coastal beaches, sand dunes, thickets; 0–10 m; of conservation concern; Fla.; Mexico; West Indies; Central America.
Euphorbia trichotoma is found in coastal peninsular Florida from Hillsborough County south to Key West.