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Curtis' spurge, Sandhills spurge

San Pedro River sandmat

Habit Herbs, perennial, with spreading rootstock. Herbs, annual, with slender taproot.
Stems

erect or ascending, branched, solitary or few, previous year's dead stems not persistent, 20–40 cm, usually glabrous, rarely strigose to sericeous at nodes.

erect to ascending, 10–55 cm, glabrous.

Leaves

alternate;

stipules to 0.1 mm;

petiole to (0–)1–2 mm, glabrous or strigose to sericeous;

blade usually linear, occasionally elliptic, rarely ovate, proximal often greatly reduced and often scalelike, 10–30 × 1.5–6 mm, base cuneate, margins entire, occasionally sparsely ciliate, apex rounded or broadly acute, abaxial surface glabrous or sparsely strigose to sericeous, adaxial surface glabrous;

venation obscure, only midvein conspicuous.

opposite;

stipules distinct, narrowly triangular and often divided into 3–5 subulate to filiform segments, 0.8–1.9 mm, glabrous;

petiole 1.2–3.1 mm, glabrous;

blade oblong, elliptic, or ovate, 12–43 × 3–14 mm, base subsymmetric to asymmetric, rounded, attenuate, or with one side hemicordate and other side rounded, margins usually serrulate, rarely entire on some leaves or portion of blade, apex obtuse to acute, surfaces often with red blotch in center, glabrous; pinnately veined, often only midvein conspicuous.

Involucre

campanulate, 1–1.2 × 1.3–1.5(–1.7) mm, glabrous or strigose to sericeous on distal 1/2;

glands 5, green, reniform, 0.3 × 0.6 mm;

appendages white, semicircular, 0.3–0.4 × 0.6–0.8 mm, entire.

oblong, campanulate, or funnel-shaped, 1.5–2.6 × 1.1–2.3 mm, glabrous;

glands 4, green to yellowish or tinged with red, subcircular to oblong, 0.4–0.7 × 0.5–1 mm;

appendages absent or white, often forming narrow rim or oblong to ovate, 0–0.8 × 1.2 mm, distal margin entire.

Staminate flowers

20–25.

50–60.

Pistillate flowers

ovary glabrous or sparsely strigose to sericeous;

styles 0.6–1.1 mm, 2-fid at apex to 1/2 length.

ovary glabrous;

styles 0.5–0.6 mm, 2-fid 1/2 length.

Capsules

globose, 2.5–3.2 × 4.3–5.1 mm, glabrous or sparsely strigose to sericeous;

columella 2.4–3.1 mm.

oblate, 2.4–3.2 × 3–3.5 mm, glabrous;

columella 2.3–2.5 mm.

Seeds

usually gray to black, occasionally brown, ovoid-globose, 2.2 × 1.8 mm, smooth;

caruncle absent.

light brown, ovoid, 4-angled in cross section, abaxial keel well developed, 1.9–2.3 × 1.3–1.4 mm, finely dimpled and papillate.

Cyathia

in terminal pleiochasia (fertile axillary branches occasionally present);

peduncle 6.5–17 mm, filiform, glabrous.

solitary at distal nodes;

peduncle 1.4–2.4 mm.

Euphorbia curtisii

Euphorbia trachysperma

Phenology Flowering and fruiting early spring–summer. Flowering and fruiting late summer–early winter.
Habitat Xeric to dry oak or oak-pine scrub of sand hills, pine-oak woodlands, pine-oak savannas. Desert scrub, desert grasslands, mesquite woodlands.
Elevation 0–200 m. (0–700 ft.) 200–1200 m. (700–3900 ft.)
Distribution
from FNA
FL; GA; NC; SC
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; Mexico (Baja California Sur, Sonora)
[BONAP county map]
Discussion

Euphorbia curtisii is found in the Gulf and Atlantic coastal plains.

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

Euphorbia trachysperma may be expected in extreme southwestern New Mexico given the close proximity of some collections in southeastern Arizona.

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

Source FNA vol. 12, p. 245. FNA vol. 12, p. 291.
Parent taxa Euphorbiaceae > Euphorbia > sect. Alectoroctonum Euphorbiaceae > Euphorbia > sect. Anisophyllum
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. 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. 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
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. spathulata, E. stictospora, E. strictior, E. telephioides, E. terracina, E. tetrapora, E. texana, E. theriaca, E. thymifolia, E. tithymaloides, E. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
Synonyms E. eriogonoides, Tithymalopsis curtisii, T. eriogonoides Chamaesyce trachysperma
Name authority Engelmann ex Chapman: Fl. South. U.S., 401. (1860) Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859)
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