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sun spurge

sickle spurge

Habit Herbs, perennial, with moniliform tuberous rootstock. Herbs, annual, with taproot.
Stems

erect, 5–20(–30) cm, usually glabrous, occasionally puberulent;

branches ± straight.

erect, unbranched or branched, 5–20 cm, glabrous.

Leaves

alternate;

petiole 0–2 mm, glabrous or strigose;

blade linear-lanceolate to ovate or broadly elliptic, 25–50 × 3–20 mm, unlobed, base rounded (tapered to petiole), margins with few glandular teeth, strigillose, flat to revolute, apex acute, abaxial surface coarsely strigose, adaxial surface strigose-hirsute;

venation pinnate, midvein prominent.

petiole absent;

blade obovate, linear-oblong, or spatulate, 2–20 × 2–10 mm, base cuneate or attenuate, margins entire, apex acute, obtuse, emarginate, or mucronate, surfaces glabrous;

venation usually inconspicuous, sometimes 3-nerved from base, midvein prominent.

Involucre

broadly globose-cupulate, 1.7–2.1 × 2.2–2.5 mm, glabrous or puberulent;

involucral lobes divided into triangular segments;

glands 1–4(–5), white, sessile and broadly attached, 1.1 × 1.4 mm, opening oblong, glabrous;

appendages absent.

cupulate, 0.5–1.2 × 0.6–1.3 mm, glabrous;

glands 4, elliptic to orbiculate, 0.2–0.3 × 0.3–0.8 mm;

horns usually absent, occasionally divergent, 0.5–1.2 mm.

Staminate flowers

20–25.

6–10.

Pistillate flowers

ovary glabrous or puberulent, styles 3–4 mm, 2-fid 1/2 to nearly entire length.

ovary pilose only at base, styles 0.9–1.1 mm, 2-fid.

Capsules

depressed-globose, 3.8–5 × 4–5 mm, 3-lobed, glabrous or puberulent;

columella 3.6–4.5 mm.

subovoid, 2–3 × 1.8–3 mm, slightly lobed;

cocci rounded, smooth, glabrous or slightly pilose along abaxial region;

columella 1.1–1.8 mm.

Seeds

white, mottled brown to gray, ellipsoid, rounded in cross section, 4–4.6 × 2.4–3.2 mm, smoothly and broadly pitted or grooved;

caruncle 0.1 mm.

grayish, whitish, or light brownish, ovoid, 1.2–1.8 × 0.7–1.1 mm, transversally sulcate;

caruncle subglobose to subconic, 0.2–0.5 × 0.2–0.5 mm.

Cyathial

arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched (often highly condensed);

pleiochasial bracts 6–8(–10), as tight involucrate whorl, wholly white to pale pink or red, usually narrower than distal leaves;

dichasial bracts linear and highly reduced.

arrangement: terminal pleiochasial branches 2–5, each 2–6 times 2-branched;

pleiochasial bracts similar in shape to but usually shorter and wider than distal leaves;

dichasial bracts distinct, widely ovate, rhombic, or suborbiculate, imbricate, base cordate, truncate or cuneate, margins finely denticulate, apex acute or obtuse, strongly mucronate;

axillary cymose branches 0–10.

Cyathia

peduncle 2–5.5 mm.

peduncle 0–2 mm.

Euphorbia radians

Euphorbia falcata

Phenology Flowering and fruiting spring–summer. Flowering and fruiting spring–summer.
Habitat Pinyon-juniper woodlands, oak savannas, desert grasslands and scrub. Waste places, roadsides.
Elevation 700–2500 m. (2300–8200 ft.) 0–1600 m. (0–5200 ft.)
Distribution
from FNA
AZ; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
KY; MD; OH; PA; TN; VA; WV; s Europe; c Europe; w Asia; c Asia; s Asia; n Africa [Introduced in North America; introduced also in South America (Chile)]
[BONAP county map]
Discussion

Euphorbia radians is widely distributed but scattered from the Sonoran and Chihuahuan deserts south to Oaxaca in Mexico. The species is distinct among species in sect. Poinsettia in the flora area in its precocious habit, often flowering before the leaves emerge.

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

Source FNA vol. 12, p. 324. FNA vol. 12, p. 302.
Parent taxa Euphorbiaceae > Euphorbia > sect. Poinsettia 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. 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. 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
Synonyms Poinsettia radians Tithymalus falcatus
Name authority Bentham: Pl. Hartw., 8. (1839) Linnaeus: Sp. Pl. 1: 456. (1753)
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