Euphorbia cyathophora |
Euphorbia arizonica |
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fire on the mountain, painted leaf, painted poinsettia |
Arizona sandmat, Arizona spurge |
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Habit | Herbs, annual, with spreading taproots. | Herbs, annual or short-lived perennial, with slender to slightly thickened taproot. |
Stems | erect or ascending, 20–100 cm, glabrous, sparsely pilose, or puberulent; branches ± straight. |
erect to ascending, 10–30 cm, uniformly pilose with glistening hairs. |
Leaves | usually alternate, occasionally opposite proximally; petiole 2–20 mm, glabrous or pilose, or often hispid abaxially near blade junction; blade linear, lanceolate, elliptic, or wider leaves pandurate and unequally 4-lobed, occasionally polymorphic on single plants, 15–250 × 4–40 mm, base acute to cuneate, margins subulately glandular-serrulate distally, or sparsely glandular and subentire, hirtellous to glabrate, flat to revolute, apex acute to cuneate, abaxial surface sparsely pilose or glabrate, adaxial surface glabrous or sparsely puberulent; venation pinnate, midvein prominent. |
opposite; stipules distinct, deltate, (0–)0.1 mm, glabrous or with few scattered hairs; petiole 0.4–1.5 mm, pilose with glistening hairs; blade usually ovate, rarely elliptic, 3–11 × 2–7 mm, base asymmetric, one side cuneate to rounded, other side rounded to strongly cordate, margins entire, apex obtuse or acute, surfaces pilose with glistening hairs; 3-veined from base but usually only midvein conspicuous. |
Involucre | campanulate, occasionally broadly so, 1.8–2.8 × 2.2–2.8 mm, glabrous; involucral lobes triangularly 3–5 lobed; gland 1, yellow-green, sessile to substipitate and narrowly to broadly attached, 1–1.4 × 0.9–1.6 mm, opening oblong (flattened without pressing), without annular rim, glabrous; appendages absent. |
urceolate, 1.1–1.3 × 0.5–0.9 mm, glabrous or pilose with glistening hairs; glands 4, dark maroon, usually oblong to reniform, rarely almost circular, 0.2 × 0.2–0.4 mm; appendages white to pink, oblong, flabellate, oblong, or elliptic, 0.3–0.6 × 0.6–0.9 mm, distal margin entire or crenulate. |
Staminate flowers | 7–20. |
5–12. |
Pistillate flowers | ovary glabrous; styles 1.6 mm, 2-fid nearly entire length. |
ovary pilose, styles 0.5–0.6 mm, 2-fid 1/2 length. |
Capsules | green, depressed-globose to ellipsoid, 2.8–3.2 × 4–4.5 mm, 3-lobed, glabrous; columella 2–2.7 mm. |
broadly ovoid to subglobose, 1.4–1.8 mm diam., pilose; columella 1.1–1.4 mm. |
Seeds | black to ashy gray or light brown, cylindric to ovoid, rounded in cross section, 2.3–3.1 × 1.9–2.5 mm, uniformly tuberculate or tubercles arranged in median, transverse ridge in cylindric seeds; caruncle absent. |
gray to light brown, ovoid, 4-angled in cross section, 0.9–1.1 × 0.5–0.6 mm, rugose with 2–5 irregular transverse ridges that sometimes pass through abaxial keel. |
Cyathial | arrangement: terminal pleiochasial branches (1–)3, 1–2-branched; pleiochasial bracts 2–3(–4), often as tight, involucrate whorl, usually green with white, pink, or red at base, occasionally distal bracts wholly white, pink, or red, rarely all bracts wholly green, similar in shape and size to distal leaves; dichasial bracts often colored, similar in shape and size to distal stem leaves or highly reduced. |
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Cyathia | peduncle 1.6–2.8 mm. |
solitary at distal nodes; peduncle 0.7–3.6 mm. |
2n | = 28, 56. |
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Euphorbia cyathophora |
Euphorbia arizonica |
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Phenology | Flowering and fruiting late spring–fall. | Flowering and fruiting year-round in response to sufficient moisture. |
Habitat | Bottomland forests, stream and river banks, bases of bluffs, fallow fields, roadsides, open disturbed areas. | Washes and rocky slopes, sometimes on limestone, desert scrub communities often with creosote-bush, riparian forests, mesquite woodlands, oak chaparral. |
Elevation | 0–1800 m. (0–5900 ft.) | 100–1400 m. (300–4600 ft.) |
Distribution |
AL; AR; CA; FL; GA; IA; IL; IN; KS; KY; LA; MD; MN; MO; MS; NC; NE; NM; OH; OK; SC; SD; TN; TX; UT; VA; WI; Mexico; Central America; South America; West Indies [Introduced in Eurasia, Africa, Indian Ocean Islands, Pacific Islands, Australia]
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AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
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Discussion | Euphorbia cyathophora is native to the midwestern and southeastern United States, Mexico, the West Indies, and northern South America. Leaf shape can be polymorphic on individuals of this species, but not to the extent as in E. heterophylla. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia arizonica is distinctive and easily recognized by its glistening, translucent hairs that appear somewhat glutinous and are most apparent on the stems. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 319. | FNA vol. 12, p. 260. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Poinsettia cyathophora | Chamaesyce arizonica |
Name authority | Murray: Commentat. Soc. Regiae Sci. Gott. 7: 81, plate 1. (1786) | Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) |
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