Euphorbia crenulata |
Euphorbia micromera |
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Chinese caps, western wood spurge |
desert spurge, Sonoran sandmat, tiny sandmat |
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Habit | Herbs, usually biennial, occasionally annual, with taproot. | Herbs, annual, with slender taproot. |
Stems | erect, sometimes decumbent at base, unbranched or branched, 12–40 cm, glabrous. |
prostrate, mat-forming, 5–35 cm, glabrous or shortly pilose. |
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. |
opposite; stipules distinct, subulate, 0.2–0.4 mm, pilose; petiole 0.5–1.2 mm, glabrous or pilose; blade ovate to elliptic, 6–15 × 2–4 mm, base asymmetric, one side cuneate to rounded, other side rounded, margins entire, apex obtuse, surfaces glabrous or pilose; venation obscure or 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. |
campanulate, 0.4–0.6 × 0.5–0.9 mm, glabrous or pilose; glands 4, red, circular to oblong, 0.1 × 0.1–0.2 mm; appendages absent. |
Staminate flowers | 11–18. |
2–5. |
Pistillate flowers | ovary glabrous; styles 0.9–1.4 mm, 2-fid. |
ovary usually glabrous, rarely pilose; styles 0.1–0.2 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. |
oblong, 1.3–1.5 × 1.1–1.3 mm, usually glabrous, rarely pilose; columella 1–1.2 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. |
light gray, narrowly ovoid, 4-angled in cross section, 0.9–1 × 0.5–0.6 mm, smooth to slightly rugose or with 1–4 faint transverse ridges that do not pass through abaxial keel. |
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. |
solitary at distal nodes; peduncle 0.4–1.4 mm. |
Euphorbia crenulata |
Euphorbia micromera |
|
Phenology | Flowering and fruiting spring–summer. | Flowering nearly year-round in response to sufficient rainfall. |
Habitat | Conifer, oak, and mixed forests, coastal scrub, grasslands, barrens and outcrops, roadsides. | Desert scrub, riparian woods with ash and willow, saltbush scrub, Joshua tree woodlands and grasslands, often in sandy or gravelly areas. |
Elevation | 30–1800 m. (100–5900 ft.) | -20–1800 m. (-100–5900 ft.) |
Distribution |
CA; CO; NM; OR
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AZ; CA; NM; NV; TX; UT; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
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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.) |
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Source | FNA vol. 12, p. 301. | FNA vol. 12, p. 278. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus crenulatus | Chamaesyce micromera |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 192. (1859) | Boissier: Proc. Amer. Acad. Arts 5: 171. (1861) |
Web links |