Euphorbia chamaesula |
Euphorbia hexagona |
|
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mountain spurge |
six-angle spurge |
|
Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with taproot. |
Stems | erect, branched, 40–90 cm, glabrous. |
erect, unbranched or branched, 30–70(–100) cm, sparsely hispid, occasionally densely so at distal nodes. |
Leaves | petiole 0.5–1 mm; blade elliptic to oblong, 8–20(–40) × 3–6 mm, base truncate, rounded, or attenuate, margins entire, apex obtuse or acute, sometimes slightly mucronate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
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. |
Involucre | turbinate or campanulate, 1.5–2.5 × 1.1–1.9 mm, glabrous; glands 4, crescent-shaped to semicircular, 0.5–0.8 × 1–1.8 mm; horns usually convergent, 0.2–0.8 mm. |
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. |
Staminate flowers | 8–12. |
15–30(–40). |
Pistillate flowers | ovary glabrous; styles 1–1.8 mm, 2-fid. |
ovary glabrous; styles 0.7–1.1 mm, 2-fid nearly entire length. |
Capsules | depressed-ovoid, 4.3–5 × 5–6 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 3.5–4 mm. |
subglobose to broadly ovoid, 4.7–6.5 × 4.9–6.5(–7.1) mm, glabrous; columella 3.5–4.5 mm. |
Seeds | gray to dark brown, ovoid-oblong, truncate at both ends, 2.6–3.4 × 2–2.6 mm, shallowly pitted to almost smooth; caruncle conic, 1 × 0.8 mm. |
dark brown or dark gray, ovoid, 3.4 × 2.7 mm, rugose, whitish glaucous; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches 3–5(–6), each 3–4 times 2-branched; pleiochasial bracts ovate-lanceolate to slightly subpandurate, similar in size or wider than distal leaves; dichasial bracts distinct, lanceolate to broadly ovate, base usually truncate to rounded or subcordate, sometimes attenuate, margins entire or slightly crenulate, apex usually obtuse to acute, occasionally acuminate; axillary cymose branches 2–8. |
|
Cyathia | peduncle 1–3 mm. |
solitary in leaf axils or in terminal cymes or dichasia; peduncle 1–2.1 mm, strigillose. |
2n | = 26. |
|
Euphorbia chamaesula |
Euphorbia hexagona |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting late summer–fall. |
Habitat | Clearings in ponderosa pine forests, montane roadsides, dry streambeds, creek banks, sandy and gravelly soils. | Sand prairies, other sandy soil habitats, stream banks, sand bars, damp places. |
Elevation | 1700–2700 m. (5600–8900 ft.) | 200–1300 m. (700–4300 ft.) |
Distribution |
AZ; NM; Mexico (Chihuahua, Sonora)
|
AR; CO; IA; IL; KS; MN; MO; MT; NE; NM; OK; SD; TX; WI; WY
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Discussion | Euphorbia chamaesula is easily distinguished from other perennial members of subg. Esula in western North America by its larger capsules and the vegetative shoots (without cyathia) that arise from the distal nodes of the stem proximal to the pleiochasia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 300. | FNA vol. 12, p. 247. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Tithymalus chamaesula | |
Name authority | Boissier: Cent. Euphorb., 38. (1860) | Nuttall ex Sprengel: Syst. Veg. 3: 791. (1826) |
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