Euphorbia capitellata |
Euphorbia ipecacuanhae |
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capitate sandmat, head sandmat, head spurge |
American ipecac, Carolina ipecac, ipecac spurge |
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Habit | Herbs, annual or perennial, with slender to thick and woody rootstock. | Herbs, perennial, with deep, stout rootstock. |
Stems | usually ascending (but ranging from decumbent to erect), 15–50 cm, glabrous, strigillose, or pilose. |
decumbent or slightly ascending, branched, often densely clumped, previous year's dead stems not persistent, 17–27 cm, usually glabrous, rarely sparsely villous. |
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 0.1–0.2 mm; petiole (0–)1–2 mm, glabrous; blade usually linear, obovate, or oblanceolate to orbiculate, rarely filiform, proximal greatly reduced, scalelike, 15–70 × 1.5–13 mm gradually smaller proximally, base cuneate, margins entire, apex rounded, broadly acute, or emarginate, surfaces glabrous; venation occasionally obscure on smaller leaves, midvein conspicuous. |
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. |
yellow or yellow-green, hemispheric, 1–1.2 × 2–2.4 mm, glabrous; glands 5, yellow or yellow-green, obovate or elliptic, 0.7–0.8 × 1–1.2 mm; appendages white or green, often forming narrow rim around distal margin of gland, 0–0.2 mm, entire. |
Staminate flowers | 25–40. |
10–20. |
Pistillate flowers | ovary glabrous or pilose; styles 0.4–0.6 mm, 2-fid entire length. |
ovary glabrous; styles 0.4–0.8 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, 2.3–3.4 × 3.5–4.2 mm, glabrous; columella 3–3.1 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. |
white or brown, ovoid, 2.3–2.5 × 1.5 mm, angular, with 5 longitudinal ridges, shallowly and irregularly pitted; 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. |
usually in terminal dichasia, sometimes pleiochasia; peduncle 10–50(–70) mm, glabrous. |
2n | = 14. |
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Euphorbia capitellata |
Euphorbia ipecacuanhae |
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Phenology | Flowering and fruiting year-round in response to sufficient moisture. | Flowering and fruiting early spring–early summer. |
Habitat | Gravelly washes, rocky slopes, basaltic talus, disturbed roadsides, primarily desert scrub, desert grasslands, riparian forests, rarely oak-juniper woodlands. | Pine and pine-oak savannas, pine-oak sand hills, turkey oak scrub, open sand habitats. |
Elevation | 600–1600 m. (2000–5200 ft.) | 0–150 m. (0–500 ft.) |
Distribution |
AZ; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Sinaloa, Sonora)
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CT; DC; DE; GA; MD; NC; NJ; NY; PA; SC; VA
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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.) |
The vegetative stems of Euphorbia ipecacuanhae are often quite short in proportion to the dichasial or pleiochasial branches, thus superficially plants often appear to have mostly opposite leaves. However, careful examination of the base of the plant will reveal alternate leaves. The leaves are extremely variable in both shape and coloration, and the variation can be pronounced within a population or even on a single plant. M. J. Huft (1979) did not recognize infraspecific taxa within E. ipecacuanhae, and his treatment is followed here. This species is found on the Atlantic coastal plain. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 262. | FNA vol. 12, p. 247. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Chamaesyce capitellata, C. pycnanthema, E. pycnanthema | E. arundelana, Tithymalopsis ipecacuanhae |
Name authority | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 188. (1859) | Linnaeus: Sp. Pl. 1: 455. (1753) |
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