Euphorbia spathulata |
Euphorbia terracina |
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prairie spurge, reticulate seed spurge, spatulate leaf spurge, warty spurge |
carnation spurge, Geraldton carnation weed, terracina spurge |
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Habit | Herbs, usually annual, rarely biennial, with taproot. | Herbs, perennial or biennial, with taproot. |
Stems | erect or ascending, unbranched or branched, 10–70 cm, glabrous. |
erect, unbranched or branched, 10–100 cm, glabrous. |
Leaves | petiole absent or to 0.2 mm; blade oblanceolate, oblong-oblanceolate, spatulate, or cuneate, 10–50 × 6–11 mm, base broadly attenuate to rounded or shallowly cordate-clasping, margins finely serrulate (usually distally), apex usually rounded to obtuse, occasionally slightly retuse or obcordate proximally, bluntly mucronate, surfaces glabrous; venation pinnate, midvein prominent. |
petiole absent; blade linear, linear-lanceolate, oblong-elliptic, or obovate, 4–50 × 2–10 mm, base obtuse or truncate, margins finely serrulate, apex acute, obtuse, or truncate, sometimes mucronulate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
Involucre | campanulate to cupulate, 0.6–1(–1.5) × 0.8–1.2 mm, glabrous; glands 4–5, elliptic, oblong, to slightly reniform, 0.2–0.6 × 0.4–1 mm; horns absent. |
cupulate to slightly turbinate, 1.1–2 × 1.3–1.5 mm, glabrous or puberulent; glands 4, elliptic to trapezoidal, 0.6–0.8 × 1–2 mm; horns slightly convergent to divergent, 1–2 mm. |
Staminate flowers | 3–10. |
15–20. |
Pistillate flowers | ovary glabrous; styles 0.8–1.5 mm, 2-fid. |
ovary glabrous; styles 1–1.8 mm, 2-fid. |
Capsules | depressed-globose, 2–3.5 × 4 mm, 3-lobed; cocci rounded, verrucose, verrucae 0.1–0.2 mm, glabrous; columella 1.4–2.2 mm. |
depressed-globose, 2.5–3 × 3–4.5 mm, deeply 3-lobed; cocci rounded to subangular, smooth, glabrous; columella 1.9–2.3 mm. |
Seeds | red-brown to dark purple, occasionally ± glaucous, broadly ellipsoid-ovoid to nearly globose, 1.3–2.5 × 1.5–1.8 mm, smooth, reticulate, or finely low-ridged; caruncle irregularly reniform to round, subconic to lenticular, 0.3–0.4 × 0.5–0.6 mm. |
pale gray, subovoid, 1.6–2.4 × 1.3–1.8 mm, smooth; caruncle boat-shaped, 0.4–0.6 × 0.4–0.6 mm. |
Cyathial | arrangement: terminal pleiochasial branches 3(–5), each 1–3 times 2-branched; pleiochasial bracts broadly ovate to ovate-oblong, shorter and wider than distal leaves; dichasial bracts distinct, broadly ovate, ovate-triangular, or ovate-elliptic, base cordate-clasping or subcordate to rounded, margins serrulate, apex rounded to obtuse or acute; axillary cymose branches (0–4)5–12. |
arrangement: terminal pleiochasial branches 2–5, each 1–5 times 2-branched; pleiochasial bracts lanceolate, elliptic or ovate, similar in size to distal leaves; dichasial bracts distinct, ovate to subreniform, base cuneate to cordate, margins finely serrulate, apex acute, obtuse, or rounded, sometimes mucronulate or cuspidate; axillary cymose branches 0–7. |
Cyathia | peduncle 0.3–1(–1.5) mm. |
peduncle 1–3 mm. |
Euphorbia spathulata |
Euphorbia terracina |
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Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–summer. |
Habitat | Forests, fallow fields, prairies, pastures, glades, stream banks, waste places, roadsides. | Edges of cultivated fields and woodlands, roadsides, waste areas, pastures, coastal bluffs, dunes, riparian areas. |
Elevation | 0–3500 m. (0–11500 ft.) | 0–300 m. (0–1000 ft.) |
Distribution |
AL; AR; AZ; CA; CO; DC; FL; GA; IA; ID; IL; IN; KS; KY; LA; MD; MI; MN; MO; MS; MT; NC; ND; NE; NM; OH; OK; OR; PA; SC; SD; TN; TX; UT; VA; WA; WI; WV; WY; ON; Mexico (Chihuahua, Sonora); s South America
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CA; Europe [Introduced in North America; introduced also in Mexico, s Africa, Australia]
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Discussion | As treated here, Euphorbia spathulata is a wide-ranging and variable species. J. B. S. Norton (1900) recognized a number of segregates (for example, E. arkansana, E. dictyosperma, and E. obtusata) all of which are included here in a broadly defined E. spathulata. The only segregate species that has been widely recognized in regional floras is E. obtusata (for example, M. L. Fernald 1950; T. S. Cooperrider 1995; G. Yatskievych 1999–2013, vol. 2). Authors have generally distinguished the eastern North American E. obtusata from the western E. spathulata by the former's larger seeds (1.7–2.3 mm versus 1.5–1.7 mm) with smooth (versus reticulate) surfaces, larger involucres, red (versus yellow) involucral glands, and cordate-clasping (versus rounded to subcordate) dichasial bracts. Examination of specimens of E. spathulata in the broad sense from throughout North America showed that there is some geographic patterning to seed size and surface sculpturing, but the variation does not segregate cleanly into two discrete taxa. Plants from western North America typically have small seeds (1.5–1.7 mm) with reticulate surfaces, although some western individuals have seeds 1.8–1.9 mm long with reticulate surfaces. Plants from Texas generally have small seeds (1.5–1.6 mm) but with the surfaces either reticulate or completely smooth. Plants from adjacent Louisiana have small seeds with faintly reticulate to almost bumpy surfaces. Plants from eastern North America have larger seeds (2–2.3 mm) with usually smooth surfaces, although individuals from Tennessee and the Carolinas have faintly reticulate surfaces. Involucre height, gland color, and the shape of the dichasial bracts do not segregate with seed size as previous treatments have suggested. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia terracina is native to the Mediterranean region of Europe. This species is invasive and spreading rapidly, displacing native coastal scrub in southern California, and has been listed as a noxious weed by that state. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 309. | FNA vol. 12, p. 310. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > subg. Esula |
Sibling taxa | ||
Synonyms | E. arkansana, E. dictyosperma, E. obtusata, Galarhoeus arkansanus, G. obtusatus, Tithymalus arkansanus, T. dictyospermus, T. obtusatus, T. spathulatus | Tithymalus terracinus |
Name authority | Lamarck: in J. Lamarck et al., Encycl. 2: 428. (1788) | Linnaeus: Sp. Pl. ed. 2, 1: 654. (1762) |
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