Euphorbia alta |
Euphorbia helleri |
|
---|---|---|
giant spurge, roughpod spurge, tall spurge, warty spurge |
Heller's spurge |
|
Habit | Herbs, annual or biennial, with taproot. | Herbs, annual, with taproot. |
Stems | erect, branched, 20–60 cm, glabrous. |
ascending, branched proximally, 15–30 cm, glabrous. |
Leaves | petiole 0–1 mm; blade oblong-spatulate, 20–50 × 7–18 mm, base broadly attenuate, margins serrulate, apex rounded to obtuse, surfaces glabrous, ± glaucous; venation pinnate, midvein prominent. |
petiole usually 1–3 mm, absent distally; blade spatulate, 6–15 × 3–5 mm, base broadly attenuate, margins entire, apex usually obtuse to rounded, sometimes retuse, surfaces glabrous; venation pinnate, midvein prominent. |
Involucre | narrowly campanulate, 0.8–1.1 × 1.1–1.3 mm, glabrous; glands 4, elliptic, 0.3–0.5 × 0.5–0.7 mm; horns absent. |
campanulate, 0.9–1.2 × 0.7–1 mm, glabrous; glands 4, elliptic, 0.1–0.2 × 0.3–0.4 mm; horns slightly divergent, 0.1–0.2 mm. |
Staminate flowers | 5–10. |
8–10. |
Pistillate flowers | ovary glabrous; styles 0.5–0.9 mm, 2-fid. |
ovary glabrous; styles 0.4–0.5 mm, 2-fid. |
Capsules | depressed-globose, 2–3 × 2.5–3.5 mm, 3-lobed; cocci rounded, papillate, papillae 0.2–0.5 mm, glabrous; columella 1.5–1.9 mm. |
depressed-globose, 2.1–2.5 × 2.5–3 mm, 3-lobed; cocci flattened, smooth, glabrous; columella 1.2–1.7 mm. |
Seeds | purple-black, ovoid, 1.6–2 × 1.3–1.7 mm, reticulate and areolate; caruncle reniform, flat, 0.5 × 0.7 mm. |
white to light gray, ovoid, 1.4–1.6 × 1–1.2 mm, smooth; caruncle 2-lobed, thin, 0.4 × 0.7 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3, 2–3 times 2-branched; pleiochasial bracts elliptic-oblanceolate to oblong, similar in size to distal leaves; dichasial bracts distinct, broadly ovate to orbiculate/reniform, base obtuse, margins serrulate, apex obtuse to rounded and often mucronulate; axillary cymose branches 6–20(–25). |
arrangement: terminal pleiochasial branches 3, each 1–5 times 2-branched; pleiochasial bracts oblong, similar in size to distal leaves; dichasial bracts distinct, orbiculate-ovate to nearly reniform, subpandurate, base broadly cuneate to truncate, margins entire, apex obtuse, mucronate; axillary cymose branches 0–5. |
Cyathia | peduncle 0.5–1 mm. |
peduncle 0.2–0.4 mm. |
Euphorbia alta |
Euphorbia helleri |
|
Phenology | Flowering and fruiting summer. | Flowering and fruiting late winter–spring. |
Habitat | Montane pine-oak and mixed conifer forests, disturbed roadsides, logged areas. | Forests, stream banks, roadsides, shaded areas with sandy, calcareous soils. |
Elevation | 1500–3000 m. (4900–9800 ft.) | 0–50 m. (0–200 ft.) |
Distribution |
AZ; NM; Mexico
|
LA; TX; Mexico (Nuevo León) |
Discussion | Euphorbia alta is a montane species from southern Arizona, New Mexico, and northern and central Mexico that is very similar to and sometimes difficult to distinguish from E. spathulata. Euphorbia alta tends to be a robust biennial, whereas E. spathulata is strictly annual. The most consistent characteristic to separate these two species is that the ovaries and capsules of E. alta are distinctly papillate, with the papillae rising sharply above the surface, whereas the ovaries and capsules of E. spathulata are merely verrucose, with the protuberances lower and rounded. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The smooth, white to light gray seeds of Euphorbia helleri easily distinguish it from other annual members of subg. Esula in North America. Collections of E. helleri have been made near Brownsville, Texas, and thus it is possible that the species occurs in northern Tamaulipas, Mexico. The Louisiana record (Webster Parish) likely represents introduced plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 298. | FNA vol. 12, p. 303. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Tithymalus altus | Tithymalus helleri |
Name authority | Norton: N. Amer. Euphorbia, 24, plate 24. (1899) | Millspaugh: Bot. Gaz. 26: 268, fig. [p. 270]. (1898) |
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