Euphorbia hirta |
Euphorbia yaquiana |
|
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pillpod sandmat, pillpod spurge |
hairy Mojave spurge |
|
Habit | Herbs, annual or perennial, with slender to thickened taproot. | Herbs, perennial, with thick rootstock. |
Stems | usually erect to ascending, rarely prostrate or decumbent, 10–50(–75) cm, usually both strigillose and hirsute. |
slender, erect or ascending, sometimes sinuous, densely branched near base, 10–50 cm, moderately to densely puberulent to lanulose. |
Leaves | opposite; stipules usually distinct, rarely connate at base, undivided or divided into 2–4 narrowly deltate to linear-subulate segments, 0.5–1.8(–2.9) mm, pilose, often with light-colored, minute circular glands at base; petiole 1–3 mm, usually both strigillose and hirsute; blade ovate to rhombic, 7–43 × 3–18 mm, base strongly asymmetric, one side rounded or slightly cordate to truncate, the other cuneate to attenuate, margins serrulate to double serrulate, apex acute, surfaces often with red spot in center, usually strigose to hirtellous, rarely glabrescent; 3–5-veined from base. |
petiole 0–1 mm; blade usually lanceolate or elliptic-lanceolate, sometimes slightly oblanceolate, 8–30 × 6–14 mm, base usually acute, occasionally short-attenuate, rarely obtuse, margins entire, apex usually acute, occasionally obtuse, acuminate, or cuspidate, surfaces sparsely to moderately puberulent to lanulose; venation pinnate, sometimes obscure, midvein prominent. |
Involucre | obconic, 0.6–1.2 × 0.4–0.9 mm, strigillose; glands 4, greenish to pink, circular, oblong, or reniform, 0.1–0.2 × 0.1–0.2 mm; appendages white to pink, flabellate, subcircular, or transversely oblong, rarely absent, (0–)0.1–0.6 × (0–)0.1–0.7 mm, distal margin usually entire, rarely slightly lobed. |
campanulate to broadly turbinate, 2.2–3 × 2–2.5 mm, puberulent to lanulose; glands 4, semicircular, trapezoidal, or elliptic-truncate, 0.8–1.5 × 1–2.2 mm, margins strongly crenate or dentate; horns usually absent, if present then straight, 0.1–0.2 mm, generally equaling teeth on gland margin. |
Staminate flowers | 2–8. |
12–20. |
Pistillate flowers | ovary strigillose, often canescent when young; styles 0.2–0.6 mm, 2-fid 1/2 length. |
ovary usually puberulent, occasionally lanulose; styles 1–1.2 mm, 2-fid. |
Capsules | subglobose to slightly oblate, 1–1.3 × 1.1–1.6 mm, strigillose; columella 0.7–1 mm. |
oblong-ovoid, 3.5–4 × 3–4 mm, 3-lobed; cocci rounded, smooth, usually puberulent, occasionally lanulose; columella 2.5–3 mm. |
Seeds | brownish red to orange or pink, narrowly ovoid, 4-angled in cross section, 0.7–0.9 × 0.5–0.7 mm, usually rugulose or with 3–6 low transverse ridges, rarely nearly smooth. |
gray to whitish, oblong cylindric, 2–3 × 1.5–1.8 mm, irregularly shallowly pitted to almost smooth; caruncle conic, 0.6 × 0.6 mm. |
Cyathia | in dense, axillary and terminal, capitate glomerules, with reduced, bractlike leaves subtending cyathia, axillary glomerules either sessile or at tips of elongated, leafless stalks; peduncle 0.4–2.1 mm. |
peduncle 0.3–0.8 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3–5, each 1–2 times 2-branched; pleiochasial bracts broadly ovate to subcordate, usually similar in size to, occasionally wider than, distal leaves; dichasial bracts distinct, broadly ovate to almost reniform, base obtuse, margins entire, apex obtuse, acuminate to cuspidate; axillary cymose branches 0–5. |
|
Euphorbia hirta |
Euphorbia yaquiana |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting spring–summer. |
Habitat | Disturbed areas, roadsides, vacant lots, desert grasslands, mesquite woodlands, riparian forests with cottonwoods and willows, flood plain forests, pinelands, deciduous forests. | Ponderosa pine forests, oak-pine mixed forests, dry stream banks and beds, open scrub areas, roadsides. |
Elevation | 0–1500 m. (0–4900 ft.) | 1000–2200 m. (3300–7200 ft.) |
Distribution |
AL; AR; AZ; CA; FL; GA; LA; MS; NC; NM; NY; SC; TX; Mexico; Central America; South America; West Indies; Bermuda [Introduced in North America; introduced also in Europe, Asia, Africa, Australia]
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AZ |
Discussion | Euphorbia hirta is a widespread weed that is distributed throughout tropical and subtropical regions of the world. It is probably native to at least central Mexico, and its native range possibly extends from South America to the southern United States. In many places within the flora area the species is certainly introduced, and it has been recorded as a waif from several states (for example, Maryland, Michigan, and Virginia). Euphorbia pilulifera Linnaeus, a rejected name that is a heterotypic synonym of the Asian E. parviflora Linnaeus, has been misapplied to North American material of E. hirta in the past. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia yaquiana is endemic to Pima and Graham counties in southern Arizona and is known only from the Santa Catalina and Pinaleño mountains. Records of E. yaquiana from southwestern Colorado (as E. incisa var. mollis) likely represent misidentifications of E. brachycera; therefore, those disjunct occurrences have been excluded here from the distribution of E. yaquiana. Euphorbia yaquiana has often been treated as a synonym of E. schizoloba var. mollis, but molecular phylogenetic data show that it is more closely related to E. brachycera and E. chamaesula (J. A. Peirson et al. 2014). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 271. | FNA vol. 12, p. 313. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | Chamaesyce gemella, C. hirta, E. gemella | E. schizoloba var. mollis, E. incisa var. mollis |
Name authority | Linnaeus: Sp. Pl. 1: 454. (1753) | Tidestrom: Proc. Biol. Soc. Wash. 48: 41. (1935) |
Web links |