Euphorbia spathulata
Euphorbia corollata
prairie spurge, reticulate seed spurge, spatulate leaf spurge, warty spurge
eastern flowering spurge, flowering spurge, floweringspurge euphorbia
erect or ascending, unbranched or branched, 10–70 cm, glabrous.
erect or ascending, usually unbranched, occasionally few branched, solitary or few, previous year's dead stems not persistent, 20–100 cm, glabrous or slightly pilose to villous.
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.
alternate, ascending;
stipules 0.1–0.2 mm;
petiole minute or absent;
blade oblanceolate, obovate, or elliptic, 25–55 × 5–12 mm, base cuneate to rounded, margins entire, occasionally slightly revolute, apex rounded to subacute, abaxial surface glabrous or pilose to villous, adaxial surface usually glabrous, rarely villous;
venation occasionally obscure on small leaves, midvein conspicuous.
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.
campanulate, 1.2–1.5 × 1.2–1.5(–2) mm, glabrous or moderately puberulent (especially near glands);
glands 5, green, reniform, 0.5 × 0.8–1 mm;
appendages white, flabellate, 2.5–3.5(–4.5) × 2.5–3.2 mm, entire.
3–10.
20–25.
ovary glabrous;
styles 0.8–1.5 mm, 2-fid.
ovary glabrous;
styles 0.8–1.4 mm, 2-fid at apex to 1/2 length.
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.
globose, 2.3–3 × 3.5–4.2 mm, glabrous;
columella 2–2.5 mm.
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.
white or light gray, ovoid, 2.5–2.8 × 2.2 mm, with shallow and coarse depressions;
caruncle absent.
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.
peduncle 0.3–1(–1.5) mm.
in terminal pleiochasia, dichasial bracts occasionally whorled or rarely alternate;
peduncle (1.5–)5–11(–13) mm (proximal to 70 mm), glabrous.
Euphorbia spathulata
Euphorbia corollata
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 corollata is morphologically variable and widely distributed across a large part of eastern North America. The species appears to be expanding its range, as adventive populations have been reported from disturbed habitats at the northern edge of its range in Maine, Massachusetts, Michigan, Minnesota, New Hampshire, South Dakota, and Vermont.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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