Euphorbia graminea |
Euphorbia yaquiana |
|
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grassleaf spurge |
hairy Mojave spurge |
|
Habit | Herbs, usually annual, rarely perennial, with slender, rarely tuberous, taproot. | Herbs, perennial, with thick rootstock. |
Stems | erect or ascending, branched, 30–80(–110) cm, strigillose or glabrescent, sharply angled. |
slender, erect or ascending, sometimes sinuous, densely branched near base, 10–50 cm, moderately to densely puberulent to lanulose. |
Leaves | usually alternate, sometimes some opposite; stipules usually 0.2–0.5 mm, rarely rudimentary; petiole 0.4–5.9 mm, strigillose; blade ovate, elliptic, linear-elliptic, or oblong, 10–83 × 3–39 mm, base attenuate, rounded, or cuneate, margins entire, apex acute or obtuse, surfaces strigillose; venation occasionally obscure on narrow leaves, midvein conspicuous. |
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 | campanulate or obconic, 1–1.8 × 0.8–1.7 mm, glabrous or strigillose toward rim; glands (1–)2–4, yellow to greenish, elliptic or oblong, 0.1–0.3 × 0.2–0.4 mm; appendages white to tinged purple, ovate and often hoodlike or forming narrow rim around distal margin of gland, 0.3–1.6 × 0.4–0.9 mm, entire. |
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 | 30–40. |
12–20. |
Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid from 1/2 to nearly entire length. |
ovary usually puberulent, occasionally lanulose; styles 1–1.2 mm, 2-fid. |
Capsules | ovoid-oblate, 2.5–3 × 3–3.5 mm, glabrous; columella 1.6–1.9 mm. |
oblong-ovoid, 3.5–4 × 3–4 mm, 3-lobed; cocci rounded, smooth, usually puberulent, occasionally lanulose; columella 2.5–3 mm. |
Seeds | gray, brown, or nearly black, ovoid, circular or weakly angled in cross section, 1.5–1.7 × 1.3–1.5 mm, coarsely tuberculate with longitudinal rows of shallow pits; caruncle absent or punctiform, 0.1–0.2 mm. |
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 usually terminal, rarely axillary, dichasia, distal dichasial bracts often white; peduncle 0.4–4.5 mm (to 15 mm at first node of inflorescence), glabrous. |
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 graminea |
Euphorbia yaquiana |
|
Phenology | Flowering and fruiting year-round. | Flowering and fruiting spring–summer. |
Habitat | Disturbed, weedy, or urban areas. | Ponderosa pine forests, oak-pine mixed forests, dry stream banks and beds, open scrub areas, roadsides. |
Elevation | 0–500 m. (0–1600 ft.) | 1000–2200 m. (3300–7200 ft.) |
Distribution |
AR; CA; FL; LA; TX; Mexico; Central America; South America [Introduced in North America; introduced also in West Indies, Asia, Pacific Islands]
|
AZ |
Discussion | Euphorbia graminea occurs natively from northern South America to northern Mexico. The species is a variable and taxonomically complex entity whose boundaries are not well defined and are in need of further study. Euphorbia graminea is often weedy and has recently become established in warmer areas of the southern United States, where it will likely become more common in the future. In recent years, a cultivar of E. graminea has found considerable horticultural success and is marketed under the trade name "Diamond Frost." (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. 246. | FNA vol. 12, p. 313. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Alectoroctonum | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. schizoloba var. mollis, E. incisa var. mollis | |
Name authority | Jacquin: Select. Stirp. Amer. Hist., 151. (1763) | Tidestrom: Proc. Biol. Soc. Wash. 48: 41. (1935) |
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