Euphorbia hexagona |
Euphorbia trichotoma |
|
---|---|---|
six-angle spurge |
sand-dune spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, perennial, with thick rootstock. |
Stems | erect, unbranched or branched, 30–70(–100) cm, sparsely hispid, occasionally densely so at distal nodes. |
erect, branched, 15–40 cm, glabrous. |
Leaves | opposite; stipules (0–)0.1 mm; petiole 1–4 mm, pilose; blade linear-filiform, linear, or elliptic, 21–40 × 0.9–7.5 mm, base attenuate, margins entire, apex acute, abaxial surface sparsely hispidulous to strigillose, adaxial surface glabrous; venation obscure, only midvein conspicuous. |
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. |
Involucre | campanulate, 1–1.5 × (1–)1.5–1.8 mm, hispid; glands 5, green to deep red, elliptic to reniform, 0.5 × 0.8–1 mm; appendages white to green, tinged red, deltate to ovate, 0.7–1.7 × (0.9–)1.3–1.5 mm, entire. |
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 | 15–30(–40). |
8–10. |
Pistillate flowers | ovary glabrous; styles 0.7–1.1 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.2–0.4 mm, 2-fid. |
Capsules | subglobose to broadly ovoid, 4.7–6.5 × 4.9–6.5(–7.1) mm, glabrous; columella 3.5–4.5 mm. |
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 | dark brown or dark gray, ovoid, 3.4 × 2.7 mm, rugose, whitish glaucous; caruncle absent. |
white, ovoid-globose, 1.8–2 × 1.6–1.8 mm, smooth; caruncle ± rounded and flattened, 0.3 × 0.3 mm. |
Cyathia | solitary in leaf axils or in terminal cymes or dichasia; peduncle 1–2.1 mm, strigillose. |
peduncle 0.7–1 mm. |
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. |
|
Euphorbia hexagona |
Euphorbia trichotoma |
|
Phenology | Flowering and fruiting late summer–fall. | Flowering and fruiting year-round (primarily spring–summer). |
Habitat | Sand prairies, other sandy soil habitats, stream banks, sand bars, damp places. | Coastal beaches, sand dunes, thickets. |
Elevation | 200–1300 m. (700–4300 ft.) | 0–10 m. (0–0 ft.) |
Distribution |
AR; CO; IA; IL; KS; MN; MO; MT; NE; NM; OK; SD; TX; WI; WY
|
FL; Mexico; Central America; West Indies |
Discussion | Euphorbia hexagona is native to the central United States and is most common from southern South Dakota to Oklahoma and northern Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia trichotoma is found in coastal peninsular Florida from Hillsborough County south to Key West. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 247. | FNA vol. 12, p. 311. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Galarhoeus trichotomus, Tithymalus trichotomus | |
Name authority | Nuttall ex Sprengel: Syst. Veg. 3: 791. (1826) | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 48; 2(qto.): 60. (1817) |
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