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urban spurge

Roemer's spurge

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

erect or ascending, unbranched or branched, 30–90 cm, glabrous.

erect, occasionally decumbent at base, branched, 15–30 cm, glabrous.

Leaves

petiole absent;

blade oblong-elliptic, 20–65 × 9–20 mm, base truncate to auriculate, margins entire, apex obtuse to rounded, surfaces glabrous;

venation conspicuously pinnate, midvein prominent.

petiole 2–5 mm;

blade oblanceolate to obovate, 5–20 × 5–10 mm (larger leaves in distal portion of stem), base cuneate to attenuate, margins entire, apex rounded, surfaces glabrous;

venation pinnate.

Involucre

campanulate, 2.2–3 × 1.8–2 mm, glabrous;

glands 4, crescent-shaped; 0.6–1 × 1–2 mm;

horns slightly divergent to convergent, 0.1–0.2 mm.

campanulate, 1.5–2 × 1–1.6 mm, glabrous;

glands 4, elliptic to trapezoidal, 0.4–0.6 × 0.7–1.2 mm;

horns slightly convergent, 0.1–0.3 mm.

Staminate flowers

15–20.

10–12.

Pistillate flowers

ovary glabrous;

styles 1.2–2 mm, 2-fid.

ovary glabrous;

styles 0.6–1 mm, 2-fid.

Capsules

globose, 2–2.8 × 2.2–2.7 mm, 3-lobed;

cocci rounded, smooth except finely granulate toward abaxial line, glabrous;

columella 2.1–2.7 mm.

subglobose, 2–2.5 × 2.4–3 mm, slightly lobed;

cocci rounded, smooth, glabrous;

columella 1.5–1.8 mm.

Seeds

gray or whitish, ovoid-oblong, 2–2.1 × 1.2–1.3 mm, smooth;

caruncle ± rounded and flattened, 0.8 × 0.6 mm.

brown, oblong-ovoid, 1.6–1.8 × 1.4–1.5 mm, with scattered, deep and broad pits;

caruncle conic, reniform, 0.3–0.4 × 0.4–0.6 mm.

Cyathial

arrangement: terminal pleiochasial branches 8–15, 1–2 times 2-branched;

pleiochasial bracts similar in shape but shorter and narrower than distal leaves;

dichasial bracts distinct, rhombic to reniform, base obtuse, margins entire, apex obtuse, mucronate;

axillary cymose branches 12–23.

arrangement: terminal pleiochasial branches 3, 1–4 times 2-branched;

pleiochasial bracts ovate to oblong, similar in size to distal leaves;

dichasial bracts connate 1/2 length, reniform to semicircular, base truncate to perfoliate, margins entire, apex rounded to obtuse;

axillary cymose branches 0–3.

Cyathia

peduncle 0–2 mm.

peduncle 0–0.9 mm.

Euphorbia agraria

Euphorbia roemeriana

Phenology Flowering and fruiting spring–summer. Flowering and fruiting spring.
Habitat Grasslands, roadside banks, pastures. Rich calcareous soils, creek canyons.
Elevation 200–1600 m. (700–5200 ft.) 100–300 m. (300–1000 ft.)
Distribution
from FNA
KS; MT; NE; NY; PA; WA; WY; AB; SK; Europe [Introduced in North America]
[WildflowerSearch map]
[BONAP county map]
from FNA
TX
[BONAP county map]
Discussion

D. S. Correll and M. C. Johnston (1970) suggested that Euphorbia roemeriana, which is restricted to the eastern part of the Edwards Plateau, is the southern counterpart of E. commutata, to which it is morphologically very similar. However, molecular phylogenetic analyses indicate that it is most closely related to E. austrotexana and E. longicruris (J. A. Peirson et al. 2014). Euphorbia roemeriana can be distinguished from E. commutata and several of the other small, annual species of subg. Esula by its consistently connate dichasial bracts.

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

Source FNA vol. 12, p. 298. FNA vol. 12, p. 308.
Parent taxa Euphorbiaceae > Euphorbia > subg. Esula Euphorbiaceae > Euphorbia > subg. Esula
Sibling taxa
E. aaron-rossii, E. abramsiana, E. acuta, 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. 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. 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 Tithymalus agrarius Tithymalus roemerianus
Name authority M. Bieberstein: Fl. Taur.-Caucas. 1: 375. (1808) Scheele: Linnaea 22: 151. (1849)
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