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prairie spurge, reticulate seed spurge, spatulate leaf spurge, warty spurge

Habit Herbs, usually annual, rarely biennial, with taproot. Herbs, annual, with taproot.
Stems

erect or ascending, unbranched or branched, 10–70 cm, glabrous.

erect, often branched near base, 10–18 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 oblanceolate, 5–12 × 3–5 mm, base attenuate, margins entire, apex rounded, surfaces glabrous;

venation pinnate, 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.

infundibular, 1–1.1 × 0.4–0.5 mm, glabrous;

glands 4, crescent-shaped; 0.3–0.4 × 0.4–0.5 mm;

horns divergent, 0.3–0.5 mm.

Staminate flowers

3–10.

5–10.

Pistillate flowers

ovary glabrous;

styles 0.8–1.5 mm, 2-fid.

ovary glabrous;

styles 0.5 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-ovoid, 2.2–2.4 × 3.2–3.4 mm, 3-lobed;

cocci rounded, smooth, glabrous;

columella 2–2.1 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.

gray, ovoid, 1.6–1.7 × 1.4–1.6 mm, with deep, rounded pits irregularly scattered over entire surface;

caruncle reniform, subconic, 0.5–0.6 × 0.6–0.8 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 3, 1–3 times 2-branched;

pleiochasial bracts rotund-obovate, wider than distal leaves;

dichasial bracts distinct, not imbricate, broadly deltate to subreniform, base truncate to emarginate, margins entire, apex rounded to bluntly acuminate;

axillary cymose branches 0–1.

Cyathia

peduncle 0.3–1(–1.5) mm.

peduncle 0.3–0.5 mm.

Euphorbia spathulata

Euphorbia georgiana

Phenology Flowering and fruiting spring–summer. Flowering and fruiting spring.
Habitat Forests, fallow fields, prairies, pastures, glades, stream banks, waste places, roadsides. Granite outcrops.
Elevation 0–3500 m. (0–11500 ft.) 100–200 m. (300–700 ft.)
Distribution
from FNA
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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[BONAP county map]
from FNA
GA
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 georgiana is restricted to granitic outcrops; it is known from Oglethorpe and Wilkes counties (M. H. Mayfield 2013). It is similar to E. austrotexana but has larger seeds that are much more deeply pitted and leaves that are oblanceolate instead of linear-oblanceolate to linear. It is also quite distinct from the more robust, biennial or occasionally annual E. commutata, the only other closely-related species that occurs in the area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 309. FNA vol. 12, p. 303.
Parent taxa Euphorbiaceae > Euphorbia > subg. Esula Euphorbiaceae > Euphorbia > subg. Esula
Sibling taxa
E. aaron-rossii, E. abramsiana, E. acuta, E. agraria, E. albomarginata, E. alta, E. angusta, E. antisyphilitica, E. arizonica, E. astyla, E. austrotexana, E. bicolor, E. bifurcata, E. bilobata, E. blodgettii, E. bombensis, E. brachycera, E. capitellata, E. carunculata, E. chaetocalyx, E. chamaesula, E. cinerascens, E. commutata, E. conferta, E. cordifolia, E. corollata, E. crenulata, E. cumulicola, E. cuphosperma, E. curtisii, E. cyathophora, E. cyparissias, E. davidii, E. deltoidea, E. dendroides, E. dentata, E. discoidalis, E. eriantha, E. exigua, E. exserta, E. exstipulata, E. falcata, E. fendleri, E. florida, E. floridana, E. garberi, E. georgiana, E. geyeri, E. glyptosperma, E. golondrina, E. gracillima, E. graminea, E. helioscopia, E. helleri, E. heterophylla, E. hexagona, E. hirta, E. hooveri, E. humistrata, E. hypericifolia, E. hyssopifolia, E. indivisa, E. innocua, E. inundata, E. ipecacuanhae, E. jaegeri, E. jejuna, E. laredana, E. lasiocarpa, E. lata, E. lathyris, E. longicruris, E. lurida, E. macropus, E. maculata, E. marginata, E. meganaesos, E. melanadenia, E. mendezii, E. mercurialina, E. mesembrianthemifolia, E. micromera, E. misera, E. missurica, E. myrsinites, E. nephradenia, E. nutans, E. oblongata, E. ocellata, E. ophthalmica, E. ouachitana, E. parishii, E. parryi, E. pediculifera, E. peplidion, E. peplus, E. perennans, E. pergamena, E. pinetorum, E. platyphyllos, E. platysperma, E. polycarpa, E. polygonifolia, E. polyphylla, E. porteriana, E. prostrata, E. pubentissima, E. purpurea, E. radians, E. rayturneri, E. revoluta, E. roemeriana, E. rosescens, E. schizoloba, E. serpens, E. serpillifolia, E. serrata, E. serrula, E. setiloba, E. simulans, E. stictospora, E. strictior, E. telephioides, E. terracina, E. tetrapora, E. texana, E. theriaca, E. thymifolia, E. tithymaloides, E. trachysperma, E. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
E. aaron-rossii, E. abramsiana, E. acuta, E. agraria, E. albomarginata, E. alta, E. angusta, E. antisyphilitica, E. arizonica, E. astyla, E. austrotexana, E. bicolor, E. bifurcata, E. bilobata, E. blodgettii, E. bombensis, E. brachycera, E. capitellata, E. carunculata, E. chaetocalyx, E. chamaesula, E. cinerascens, E. commutata, E. conferta, E. cordifolia, E. corollata, E. crenulata, E. cumulicola, E. cuphosperma, E. curtisii, E. cyathophora, E. cyparissias, E. davidii, E. deltoidea, E. dendroides, E. dentata, E. discoidalis, E. eriantha, E. exigua, E. exserta, E. exstipulata, E. falcata, E. fendleri, E. florida, E. floridana, E. garberi, E. geyeri, E. glyptosperma, E. golondrina, E. gracillima, E. graminea, E. helioscopia, E. helleri, E. heterophylla, E. hexagona, E. hirta, E. hooveri, E. humistrata, E. hypericifolia, E. hyssopifolia, E. indivisa, E. innocua, E. inundata, E. ipecacuanhae, E. jaegeri, E. jejuna, E. laredana, E. lasiocarpa, E. lata, E. lathyris, E. longicruris, E. lurida, E. macropus, E. maculata, E. marginata, E. meganaesos, E. melanadenia, E. mendezii, E. mercurialina, E. mesembrianthemifolia, E. micromera, E. misera, E. missurica, E. myrsinites, E. nephradenia, E. nutans, E. oblongata, E. ocellata, E. ophthalmica, E. ouachitana, E. parishii, E. parryi, E. pediculifera, E. peplidion, E. peplus, E. perennans, E. pergamena, E. pinetorum, E. platyphyllos, E. platysperma, E. polycarpa, E. polygonifolia, E. polyphylla, E. porteriana, E. prostrata, E. pubentissima, E. purpurea, E. radians, E. rayturneri, E. revoluta, E. roemeriana, E. rosescens, E. schizoloba, E. serpens, E. serpillifolia, E. serrata, E. serrula, E. setiloba, E. simulans, E. spathulata, E. stictospora, E. strictior, E. telephioides, E. terracina, E. tetrapora, E. texana, E. theriaca, E. thymifolia, E. tithymaloides, E. trachysperma, E. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
Synonyms E. arkansana, E. dictyosperma, E. obtusata, Galarhoeus arkansanus, G. obtusatus, Tithymalus arkansanus, T. dictyospermus, T. obtusatus, T. spathulatus
Name authority Lamarck: in J. Lamarck et al., Encycl. 2: 428. (1788) Mayfield: J. Bot. Res. Inst. Texas 7: 639, fig. 2[row 2, left]. (2013)
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