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snow-on-the-prairie

sand-dune spurge

Habit Herbs, annual, with taproot. Herbs, perennial, with thick rootstock.
Stems

erect, unbranched or branched, 40–100 cm, pilose.

erect, branched, 15–40 cm, glabrous.

Leaves

alternate;

stipules 0.3–0.4 mm;

petiole 0.3–1 mm, pilose;

blade narrowly elliptic to lanceolate, 37–54 × 7–17 mm, base cuneate to slightly rounded, margins entire, apex aristate or acute, surfaces pilose;

venation obscure, only midvein conspicuous.

petiole absent;

blade obovate to oblanceolate, 5–20 × 2–7 mm, base broadly attenuate, margins entire, apex acute to obtuse, surfaces glabrous;

venation pinnate, very obscure, midvein prominent.

Involucre

campanulate, 2.7–3.5 × 2.2–3 mm, densely pilose;

glands 4–5, green to pale greenish yellow, reniform, 0.6–0.7 × 1.4–1.6 mm;

appendages white, obdeltate to orbiculate, 1.4–2.5 × 1.7–3 mm, dentate to erose.

hemispheric, 1–1.5 × 1.4–2 mm, glabrous;

glands 5, elliptic to slightly crescent-shaped, 0.4–0.6 × 0.9–1.1 mm;

horns divergent, 0.1–0.2 mm.

Staminate flowers

30–70.

8–10.

Pistillate flowers

ovary pilose;

styles 0.7–1.2 mm, 2-fid 1/2 length.

ovary glabrous;

styles 0.2–0.4 mm, 2-fid.

Capsules

depressed-ovoid, 3.5–7.5 × 6–8.7 mm, densely pilose;

columella 4.5–5.5 mm.

depressed-ovoid, 1.1–1.5 × 2–3 mm, strongly 3-lobed;

cocci rounded, minutely papillate, sometimes appearing smooth, glabrous;

columella 1.6–1.9 mm.

Seeds

tan to brown, ovoid, 4.3–4.5 × 3.7–3.9 mm, alveolate;

caruncle absent.

white, ovoid-globose, 1.8–2 × 1.6–1.8 mm, smooth;

caruncle ± rounded and flattened, 0.3 × 0.3 mm.

Cyathia

in terminal pleiochasia dichasial and pleiochasial bracts linear to narrowly oblanceolate, with conspicuous white margins;

peduncle 1.2–3 mm, densely pilose.

peduncle 0.7–1 mm.

Cyathial

arrangement: terminal pleiochasial branches 3, each usually 1–2 times 3-branched, sometimes unbranched;

pleiochasial bracts similar in shape and size to distal leaves, alternate;

dichasial bracts distinct, obovate to oblanceolate, base broadly attenuate, margins entire, apex acute to obtuse;

axillary cymose branches 0.

Euphorbia bicolor

Euphorbia trichotoma

Phenology Flowering and fruiting summer–fall. Flowering and fruiting year-round (primarily spring–summer).
Habitat Prairies, blackland (calcareous) prairies, pastures and clearings in former blackland prairie areas, roadside clearings. Coastal beaches, sand dunes, thickets.
Elevation 100–200 m. (300–700 ft.) 0–10 m. (0–0 ft.)
Distribution
from FNA
AR; LA; OK; TX
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; Mexico; Central America; West Indies
[BONAP county map]
Discussion

Euphorbia bicolor is similar in appearance to E. marginata but can be distinguished by its linear to narrowly oblanceolate bracts and the presence of hairs on all parts of the plant.

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

Euphorbia trichotoma is found in coastal peninsular Florida from Hillsborough County south to Key West.

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

Source FNA vol. 12, p. 243. FNA vol. 12, p. 311.
Parent taxa Euphorbiaceae > Euphorbia > sect. Alectoroctonum 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. 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. 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. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
Synonyms Galarhoeus trichotomus, Tithymalus trichotomus
Name authority Engelmann & A. Gray: Boston J. Nat. Hist. 5: 233. (1845) Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 2(fol.): 48; 2(qto.): 60. (1817)
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