Euphorbia crenulata |
Euphorbia aaron-rossii |
|
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Chinese caps, western wood spurge |
Marble Canyon spurge, Ross' or Marble Canyon spurge |
|
Habit | Herbs, usually biennial, occasionally annual, with taproot. | Herbs, perennial, with deep stout rootstock. |
Stems | erect, sometimes decumbent at base, unbranched or branched, 12–40 cm, glabrous. |
erect, branched, densely clumped, previous year’s dead stems persistent, 25–45(–60) cm, glabrous, striate. |
Leaves | petiole 0–2 mm; blade obovate-spatulate to oblanceolate, 8–22 × 3–10 mm, base broadly attenuate, margins entire or slightly crisped, apex obtuse to ± rounded, minutely apiculate, surfaces glabrous; venation pinnate, midvein prominent. |
alternate, persisting, usually reflexed, occasionally spreading; stipules 0.1–0.3 mm; petiole 0.2–2.2 mm, glabrous; blade narrowly ovate to lanceolate proximally, narrowly lanceolate, linear, or filiform distally, 10–32 × 0.5–6.5 mm, base cuneate, margins entire, apex acute, surfaces pilose when young, sparsely strigose or glabrous with age; venation obscure, only midvein conspicuous. |
Involucre | campanulate, 1.8–2.1 × 1.6–1.8 mm, glabrous; glands 4, crescent-shaped, 0.6–1.2 × 1.5–2.3 mm; horns slightly divergent to slightly convergent, 0.4–0.6 mm. |
turbinate to campanulate, 2.2–3.7 × 1.5–2.5 mm, moderately strigose; glands 5, dark green, reniform, 0.7–1.1 × 1–1.6 mm; appendages white to pink, flabellate, 0.5–1.5 × 0.8–2.2 mm, dentate or erose. |
Staminate flowers | 11–18. |
20–25. |
Pistillate flowers | ovary glabrous; styles 0.9–1.4 mm, 2-fid. |
ovary strigose; styles 1–1.3 mm, 2-fid at apex. |
Capsules | subovoid, 2.5–3 × 3.5–4 mm, 3-lobed; cocci rounded, smooth or puncticulate, glabrous; columella 1.9–2.3 mm. |
subglobose, 2–3 × 4 mm, sparsely strigose; columella 2–3 mm. |
Seeds | cream and brown mottled, oblong-ovoid to nearly globose, 2–2.5 × 1.4–1.7 mm, usually irregularly vermiculate-ridged and large-pitted, occasionally tuberculate or nearly smooth; caruncle reniform, conic, 0.5–0.6 × 0.5–0.7 mm. |
gray-green to gray-brown, globose-ovoid, 1.8–2.2 × 1.2–1.6 mm, longitudinally pitted; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches 3, each 2-branched; pleiochasial bracts obovate to orbiculate-reniform, wider than distal leaves; dichasial bracts usually connate 1/3–1/2 length (often only on one side), rarely only connate basally, triangular ovate to reniform, base truncate to perfoliate, margins erose-denticulate to subentire, apex rounded to obtuse, rarely apiculate; axillary cymose branches 0–5. |
|
Cyathia | peduncle 0–0.5 mm. |
in terminal monochasia (thus appearing solitary at alternate nodes); peduncle 0.5–2.5 (or 10–25) mm, glabrous or sparsely strigose. |
Euphorbia crenulata |
Euphorbia aaron-rossii |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–fall. |
Habitat | Conifer, oak, and mixed forests, coastal scrub, grasslands, barrens and outcrops, roadsides. | Sandy soils and dunes, occasionally rocky slopes, riparian areas. |
Elevation | 30–1800 m. (100–5900 ft.) | 600–1300 m. (2000–4300 ft.) |
Distribution |
CA; CO; NM; OR
|
AZ |
Discussion | Euphorbia crenulata is most common in the central valleys of California and southern Oregon; it occurs disjunctly in southwestern Colorado and northwestern New Mexico. Previous reports from Arizona are based on misidentified specimens. Euphorbia crenulata is closely related to E. commutata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia aaron-rossii is restricted to the banks of the Colorado River in several small areas of the Grand and Marble canyons. The species is most closely related to E. strictior and E. wrightii, but due to its rarity, it has not been extensively studied. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 301. | FNA vol. 12, p. 242. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Tithymalus crenulatus | |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 192. (1859) | A. H. Holmgren & N. H. Holmgren: Brittonia 40: 357, figs. 1, 2. (1988) |
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