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coastal sand spurge, maroon or purple sand spurge

San Pedro River sandmat

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

erect or ascending, unbranched or branched, solitary, few, or occasionally densely clumped, previous year's dead stems not persistent, 20–33 cm, usually glabrous, rarely sparsely villous, glaucescent.

erect to ascending, 10–55 cm, glabrous.

Leaves

alternate;

stipules less than 0.1 mm;

petiole (0–)1–3 mm, glabrous;

blade linear or linear-elliptic to obovate or orbiculate, proximal greatly reduced, scalelike, 15–30 × 1–20 mm, base cuneate to rounded, margins entire, apex rounded, broadly acute, or emarginate, surfaces glabrous, glaucescent;

venation often obscure on narrow leaves, 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

usually dark red, campanulate, 1.3–1.6 × 1.4–2.1 mm, glabrous;

glands 5, usually dark red, rarely greenish red, elliptic reniform, thickened, 0.3–0.5 × 0.8 mm;

appendages white or green, often forming narrow rim around distal margin of gland, 0–0.2 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;

styles 0.4–0.8 mm, 2-fid at apex.

ovary glabrous;

styles 0.5–0.6 mm, 2-fid 1/2 length.

Capsules

depressed-globose, 1.8–2.5 × 3.6–4.4 mm, glabrous;

columella 1.9–2.4 mm.

oblate, 2.4–3.2 × 3–3.5 mm, glabrous;

columella 2.3–2.5 mm.

Seeds

ashy white, ovoid, 2.1 × 1.3 mm, angled with 5 blunt longitudinal ridges, with shallow and irregular pits;

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

usually in terminal dichasia, sometimes pleiochasia;

peduncle 6–33 mm, filiform, glabrous.

solitary at distal nodes;

peduncle 1.4–2.4 mm.

Euphorbia exserta

Euphorbia trachysperma

Phenology Flowering and fruiting spring–summer. Flowering and fruiting late summer–early winter.
Habitat Xeric to dry pine-oak scrub of sand hills, pine-oak woodlands, pine-oak savannas. Desert scrub, desert grasslands, mesquite woodlands.
Elevation 0–150 m. (0–500 ft.) 200–1200 m. (700–3900 ft.)
Distribution
from FNA
FL; GA; NC; SC; VA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; Mexico (Baja California Sur, Sonora)
[BONAP county map]
Discussion

K. R. Park (1998) recognized both Euphorbia exserta and E. gracilior as distinct species, with the former known only from the holotype. However, this treatment follows M. J. Huft (1997) and treats E. gracilior as a synonym of E. exserta. Although the type of E. exserta is unusual in having greenish red (versus dark red) cyathia and glands, as well as small gland appendages, it is otherwise typical of the species as a whole, including features such as the upright habit, reddish coloration, scalelike proximal leaves, and filiform peduncles to 30 mm that are also common to plants formerly treated as E. gracilior. Euphorbia gracilis Elliott, which has sometimes been applied to E. exserta, is an illegitimate name (a later homonym of E. gracilis Loiseleur-Deslongchamps) and pertains here.

The upright habit and usually dark red cyathia and glands distinguish Euphorbia exserta from the otherwise similar E. ipecacuanhae, while the glaucescent vegetative parts and smaller gland appendages readily separate E. exserta from the similar E. curtisii. Euphorbia exserta is found on 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. 246. 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. curtisii, E. cyathophora, E. cyparissias, E. davidii, E. deltoidea, E. dendroides, E. dentata, E. discoidalis, E. eriantha, E. exigua, 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 Tithymalopsis exserta, E. gracilior, T. gracilis Chamaesyce trachysperma
Name authority (Small) Coker: Pl. Life Hartsville, 88. (1912) Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859)
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