Euphorbia davidii |
Euphorbia maculata |
|
---|---|---|
David's poinsettia, David's spurge, tooth poinsettia, tooth spurge |
euphorbe maculée, milk purslane, milk spurge, prostrate spurge, sandmat, spotted sandmat, spotted sandmat or spurge, spotted spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, annual, with taproot. |
Stems | erect or ascending, 20–70 cm, both coarsely and sparsely hirsute and closely strigillose; branches usually ± straight, occasionally proximal branches arcuate. |
usually prostrate, occasionally with ascending tips, often mat-forming, not rooting at nodes, 5–45 cm, densely and evenly short-sericeous to sericeous or villous. |
Leaves | usually opposite, occasionally alternate at distal nodes; petiole 7–25 mm, strigose; blade usually narrowly to broadly elliptic, occasionally lance-elliptic, 10–100 × 5–35 mm, base cuneate to attenuate, margins coarsely crenate-dentate, strigose, revolute to nearly flat, apex broadly acute to acuminate, or obtuse, abaxial surface strigose with stiff, strongly tapered hairs, adaxial surface sparsely strigose-hirsute; venation pinnate, midvein prominent. |
opposite; stipules distinct, linear-subulate, sometimes irregularly 2–3-lobed, 1–1.3 mm, sparsely short-sericeous to sericeous or villous; petiole 0.5–1.5 mm, moderately short-sericeous to sericeous or villous; blade oblong-ovate to ovate-elliptic or oblong-elliptic, 4–18 × 2.5–8 mm, base strongly asymmetric, one side usually angled and other ± truncate and expanded into small, rounded auricle, margins serrulate (longer side) or subentire (shorter side), apex rounded or broadly acute, abaxial surface pale grayish green, moderately to densely lanulose to villous, adaxial surface usually with irregular reddish streak along midvein, glabrate or with sparse, long, slender hairs; palmately veined at base, pinnate distally. |
Involucre | cylindric, 2.5–3 × 1.3–1.8 mm, glabrous; involucral lobes divided into 5–7 linear, papillate lobes; gland 1, yellow-green, sessile and broadly attached, 0.9 × 1.3 mm, opening oblong, glabrous; appendages absent. |
obconic, 0.8–1 × 0.6–0.8 mm, sparsely strigose to short-sericeous; glands 4, green to yellow-green, turning pink with age, usually ± unequal, narrowly oblong to nearly linear, 0.1–0.2 × 0.2–0.5 mm; appendages white to reddish tinged, lunate to oblong, 0.1–0.3 × 0.2–1.5 mm, distal margin crenulate. |
Staminate flowers | 5–8. |
2–5. |
Pistillate flowers | ovary glabrous or sparsely strigose; styles 1 mm, 2-fid 1/2 to nearly entire length. |
ovary sericeous; styles 0.3–0.4 mm, 2-fid at apex. |
Capsules | broadly ovoid, 2.9–3.3 × 4–4.8 mm, 3-lobed, glabrous; columella 2.2–2.7 mm. |
ovoid, well exserted from involucre at maturity, 1.3–1.5 × 1.2–1.4 mm, sparsely to moderately and evenly sericeous; columella 1–1.2 mm. |
Seeds | black to brown or pale gray, ovoid to triangular-ovoid, angular in cross section, 2.4–2.9 × 2.2–2.9 mm, low-tuberculate, tubercles irregularly arranged or in faint, transverse row; caruncle 0.9–1.1 mm. |
white to light brown, oblong-ovoid, sharply angular in cross section, 1–1.2 × 0.6–0.9 mm, with 3–4 low, transverse ridges that cross angles. |
Cyathial | arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched; pleiochasial bracts 2–4, often whorled, green with diffuse greenish white to mauve near base, similar in shape and size to distal leaves or slightly narrower; dichasial bracts similar in shape to distal leaves but smaller, often highly reduced. |
|
Cyathia | peduncle 0.5–1 mm. |
solitary or in small, cymose clusters at distal nodes or on congested, axillary branches; peduncle 0.1–0.6 mm. |
2n | = 56. |
= 28. |
Euphorbia davidii |
Euphorbia maculata |
|
Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting spring–fall. |
Habitat | Forests, stream and riverbanks, prairies, roadsides and open disturbed areas. | Disturbed areas, fallow fields, gardens, sidewalk cracks, railroads, roadsides. |
Elevation | 200–1500 m. (700–4900 ft.) | 0–1500 m. (0–4900 ft.) |
Distribution |
AR; AZ; CA; CO; FL; IA; ID; IL; IN; KS; KY; LA; MA; MI; MN; MO; NC; NE; NJ; NM; NY; OH; OK; SD; TN; TX; UT; VA; VT; WI; WV; WY; ON; QC; Mexico (Chihuahua, Coahuila, Sonora) [Introduced in South America, Eurasia (China, Russia), Australia]
|
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; BC; NB; NS; ON; PE; QC; Mexico; Central America; South America; West Indies; Eurasia; Africa; Pacific Islands (New Zealand); Australia
|
Discussion | Euphorbia davidii is native from the southwestern United States and northern Mexico north through the southern Great Plains; it apparently is adventive elsewhere. The species is the weediest member of the E. dentata species group (following M. H. Mayfield 1997) and has become an agricultural weed in North America, South America (for example, Argentina), and in the Old World (particularly Australia and Russia). Euphorbia davidii can be distinguished from the closely similar E. dentata by its larger capsules and seeds, often more elliptic leaves, and shorter, stiffer hairs. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia maculata is a widespread weed in temperate latitudes, and it also occurs in cool climates at higher elevations in the tropics. It is presumed to be native to eastern and central North America, but given its extremely weedy tendencies, it is difficult to know for sure. It spreads readily in association with greenhouse plants and earth-moving activities, and it is notorious for its ability to colonize sidewalk cracks in the summer, even in congested cities. The name E. maculata was misapplied by most earlier botanists (for example, L. C. Wheeler 1941) to plants with ascending stems that are treated here as E. nutans. D. G. Burch (1966) reviewed the sources of data used by Linnaeus in his original description and concluded that the name E. maculata applies to this prostrate-stemmed taxon. For further discussion of the distinctions between E. maculata and the similar 47. E. humistrata, see the treatment of that species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 320. | FNA vol. 12, p. 275. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Poinsettia | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Chamaesyce maculata, C. mathewsii, C. supina, C. tracyi, E. supina | |
Name authority | Subils: Kurtziana 17: 125, figs. 1, 2H–J. (1984) | Linnaeus: Sp. Pl. 1: 455. (1753) |
Web links |
|
|