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six-angle spurge

Habit Herbs, annual, with taproot. Herbs, annual, with taproot.
Stems

erect, unbranched or branched, 30–70(–100) cm, sparsely hispid, occasionally densely so at distal nodes.

erect-ascending, often basally decumbent, often branched near base, 12–28 cm, glabrous.

Leaves

opposite;

stipules (0–)0.1 mm;

petiole 1–4 mm, pilose;

blade linear-filiform, linear, or elliptic, 21–40 × 0.9–7.5 mm, base attenuate, margins entire, apex acute, abaxial surface sparsely hispidulous to strigillose, adaxial surface glabrous;

venation obscure, only midvein conspicuous.

petiole 0–3 mm;

blade broadly oblanceolate to subspatulate, or proximalmost often orbiculate, 3–20 × 3–9 mm, base attenuate, margins entire, apex rounded to emarginate, surfaces glabrous;

venation pinnate, midvein prominent.

Involucre

campanulate, 1–1.5 × (1–)1.5–1.8 mm, hispid;

glands 5, green to deep red, elliptic to reniform, 0.5 × 0.8–1 mm;

appendages white to green, tinged red, deltate to ovate, 0.7–1.7 × (0.9–)1.3–1.5 mm, entire.

infundibular, 1.3–1.6 × 1–1.2 mm, glabrous;

glands 4, crescent-shaped; 0.4–0.5 × 0.8–1 mm;

horns divergent, 0.2–0.4 mm.

Staminate flowers

15–30(–40).

15–20.

Pistillate flowers

ovary glabrous;

styles 0.7–1.1 mm, 2-fid nearly entire length.

ovary glabrous;

styles 0.8 mm, 2-fid.

Capsules

subglobose to broadly ovoid, 4.7–6.5 × 4.9–6.5(–7.1) mm, glabrous;

columella 3.5–4.5 mm.

ovoid-globose, 2.6–2.7 × 2.5–2.7 mm, slightly lobed;

cocci rounded to ± flattened, smooth, glabrous;

columella 2–2.1 mm.

Seeds

dark brown or dark gray, ovoid, 3.4 × 2.7 mm, rugose, whitish glaucous;

caruncle absent.

dark brown, oblong-ovoid, 1.5–2 × 1–1.6 mm, with deep, rounded pits in 3–4 regular vertical rows;

caruncle reniform-ovate, conic, 0.5–0.7 × 0.5–0.8 mm.

Cyathia

solitary in leaf axils or in terminal cymes or dichasia;

peduncle 1–2.1 mm, strigillose.

peduncle 0.4–0.7 mm.

Cyathial

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

pleiochasial bracts ovate-deltate to subrhombic-ovate, shorter and wider than distal leaves;

dichasial bracts connate 1/4 length, not imbricate, broadly deltate to subreniform, base truncate to broadly obtuse, margins entire, apex obtuse to bluntly acuminate;

axillary cymose branches 1–5.

2n

= 26.

Euphorbia hexagona

Euphorbia ouachitana

Phenology Flowering and fruiting late summer–fall. Flowering and fruiting spring.
Habitat Sand prairies, other sandy soil habitats, stream banks, sand bars, damp places. Semiopen forests, bluffs and ledges, stream banks, glades.
Elevation 200–1300 m. (700–4300 ft.) 100–400 m. (300–1300 ft.)
Distribution
from FNA
AR; CO; IA; IL; KS; MN; MO; MT; NE; NM; OK; SD; TX; WI; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
AR; MO; OK; TN; TX
Discussion

Euphorbia hexagona is native to the central United States and is most common from southern South Dakota to Oklahoma and northern Texas.

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

Euphorbia ouachitana is restricted to semiopen forests and woodlands in the south-central United States. It is similar to E. commutata and has been most commonly identified as that species in the past. However, it differs in its consistently brown seeds that have pits in regular, vertical rows. The two species also differ in E. commutata’s numerous, proximal, long-petiolate elliptic leaves. The proximal leaves of E. ouachitana are spatulate with an orbiculate blade and petiolelike base. Aside from the restricted distribution of E. ouachitana in Missouri and Tennessee, the ranges of E. ouachitana and E. commutata do not overlap (see M. H. Mayfield 2013 for a detailed discussion of the distribution). Euphorbia ouachitana is most common in the Ouachita Mountains from southeastern Oklahoma to Hot Springs County, Arkansas.

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

Source FNA vol. 12, p. 247. FNA vol. 12, p. 306.
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. 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. 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. 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
Name authority Nuttall ex Sprengel: Syst. Veg. 3: 791. (1826) Mayfield: J. Bot. Res. Inst. Texas 7: 642, figs. 2[row 2, right], 6. (2013)
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