Euphorbia capitellata |
Euphorbia polyphylla |
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capitate sandmat, head sandmat, head spurge |
lesser Florida spurge |
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Habit | Herbs, annual or perennial, with slender to thick and woody rootstock. | Herbs, perennial, with spreading rootstock. |
Stems | usually ascending (but ranging from decumbent to erect), 15–50 cm, glabrous, strigillose, or pilose. |
erect or ascending, branched, solitary, few, or occasionally densely clumped, previous year's dead stems not persistent, 18–33 cm, glabrous. |
Leaves | opposite; stipules distinct, filiform or divided into 2–3 subulate-filiform segments, without dark, circular glands at base, 0.6–1.5 mm, pilose; petioles 0.6–1.3 mm, glabrous, pilose, or strigillose; blade ovate to narrowly ovate, 4–19 × 2–8 mm, base asymmetric, one side strongly cordate, other side rounded to slightly cordate, margins entire or serrulate (commonly nearly entire with few scattered teeth, often slightly thickened), apex acute, surfaces often with red spot in center, glabrous, pilose, or strigillose; weakly 3-veined from base, usually only midvein conspicuous. |
alternate; stipules to 0.1 mm; petiole minute or absent; blade linear to filiform, 10–20 × 0.8–1.5(–4) mm, base cuneate, margins entire, often involute, apex rounded, surfaces glabrous; venation usually obscure, midvein visible at base of wider leaves. |
Involucre | narrowly obconic to narrowly campanulate, 0.8–1.6 × 0.7–1.3 mm, glabrous or pilose; glands 4, yellow-green to pink or maroon, circular to oblong, 0.2–0.4 × 0.2–0.5 mm; appendages white to light pink, oblong to reniform or flabellate, 0.2–1.1 × 0.5–1.7 mm, surfaces glabrous, distal margin entire. |
campanulate, 1.2–2 × 1.3–1.8 mm, glabrous or strigose on distal extreme; glands 5, red, elliptic, 0.5 × 1 mm; appendages white, orbiculate, 0.5–0.8 × 1.3–1.5 mm, erose. |
Staminate flowers | 25–40. |
20–25. |
Pistillate flowers | ovary glabrous or pilose; styles 0.4–0.6 mm, 2-fid entire length. |
ovary glabrous; styles 0.6–1 mm, 2-fid at apex. |
Capsules | ovoid to oblate, 1.3–1.9 × 1.4–2.1 mm, glabrous or pilose; columella 1.1–1.7 mm. |
globose, 2.3–2.8 × 4.3–5.1 mm, glabrous; columella 2.5–3.2 mm. |
Seeds | pink to pinkish gray, narrowly ovoid to narrowly ovoid-oblong, 4-angled or weakly 3-angled in cross section, 0.9–1.5 × 0.5–0.7 mm, irregularly dimpled, sometimes also with faint transverse ridges that do not pass through abaxial keel. |
ashy gray, ovoid, 2.9 × 2 mm, with obscure shallow depressions; caruncle absent. |
Cyathia | in dense, terminal capitate glomerules, with reduced, bractlike leaves subtending cyathia, at tips of main stems and short, leafy, axillary branches; peduncle 0.1–1.2 mm. |
in terminal dichasia or pleiochasia; peduncle 2–6 mm (to 20 mm for central cyathium), glabrous. |
2n | = 14. |
|
Euphorbia capitellata |
Euphorbia polyphylla |
|
Phenology | Flowering and fruiting year-round in response to sufficient moisture. | Flowering and fruiting late spring–late fall. |
Habitat | Gravelly washes, rocky slopes, basaltic talus, disturbed roadsides, primarily desert scrub, desert grasslands, riparian forests, rarely oak-juniper woodlands. | Open sand and pine savannas. |
Elevation | 600–1600 m. (2000–5200 ft.) | 0–10 m. (0–0 ft.) |
Distribution |
AZ; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Sinaloa, Sonora)
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FL
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Discussion | Euphorbia capitellata is a characteristic herb in the Sonoran Desert of southern Arizona, ranging east to extreme southwestern Texas. During peak flowering, plants are attractive due to the dense clusters of cyathia with well-developed involucral gland appendages. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia polyphylla is endemic to sandy habitats in the southern half of peninsular Florida. The species has been reported from coastal Louisiana, but whether those plants represent native occurrences or plantings is unclear (R. D. Thomas and C. M. Allen 1993–1998, vol. 2). The Florida populations are here recognized as the only native occurrences. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 262. | FNA vol. 12, p. 250. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Chamaesyce capitellata, C. pycnanthema, E. pycnanthema | Tithymalopsis polyphylla |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 188. (1859) | Engelmann ex Chapman: Fl. South. U.S. ed. 2, repr. 2, 694. (1892) |
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