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green poinsettia, tooth poinsettia, tooth spurge

roadside sandmat

Habit Herbs, annual, with taproot. Herbs, annual or perennial, often robust, with slender to moderately thickened taproot.
Stems

erect or ascending, 15–60 cm, both pilose and inconspicuously strigillose;

branches usually ± straight, occasionally proximal branches arcuate.

erect to ascending, 30–100 cm, pilose to tomentose.

Leaves

usually opposite, occasionally alternate at distal nodes;

petiole 5–20 mm, pilose;

blade 30–70 × 4–35 mm, narrowly lanceolate to suborbiculate, usually broadest below middle, base usually acute to subobtuse, rarely subtruncate, margins coarsely crenate-dentate or doubly crenate, strigillose, flat to slightly revolute, apex broadly acute, abaxial surface long pilose with weak, filiform hairs, adaxial surface sparsely pilose to glabrate;

venation pinnate, midvein prominent.

opposite;

stipules distinct when young, connate into deltate scale when older, erose to laciniate, with dark glands at margin or base, 0.5–1.3 mm, pilose;

petiole 0.5–2 mm, glabrescent or pilose;

blade ovate or oblong, sometimes slightly falcate, 8–46 × 3–21 mm, base asymmetric, obtuse to hemicordate, margins serrulate, apex obtuse or acute, surfaces often with red spot in center, pilose to sericeous; palmately 3–5(–7)-veined from base.

Involucre

campanulate, 3.8 × 1.8 mm, glabrous;

involucral lobes divided into several linear, smooth lobes;

glands (1–)2, green, sessile and broadly attached, 0.7–0.9 × 0.9–1.2 mm, opening oblong, glabrous;

appendages absent.

obconic, 0.9–1.3 × 0.8–1.2 mm, pilose to sericeous;

glands 4, yellow or pink, circular or oblong, 0.1–0.3 mm diam.;

appendages white or pink, oblong, flabellate, or suborbiculate, 0.1–0.6 × 0.2–1 mm, entire or crenate.

Staminate flowers

8–10.

15–25.

Pistillate flowers

ovary glabrous, styles 1.2 mm, 2-fid 1/2 to nearly entire length.

ovary densely pilose to sericeous with yellowish hairs;

styles 0.6–0.9 mm, 2-fid 1/2 length, filiform.

Capsules

depressed-globose, 2.5–2.8 × 3.5–4 mm, 3-lobed, glabrous;

columella 1.8–2.1 mm.

subglobose to broadly ovoid, 1.7–2 mm diam., pilose to sericeous with yellowish hairs;

columella 1.5–1.7 mm.

Seeds

pale gray to black, ovoid, rounded in cross section, 2.1–2.7 × 1.7–2.1 mm, evenly minute-tuberculate;

caruncle 0.4–0.6 mm.

dark reddish brown to almost black, plumply ovoid, 4-angled in cross section, 1.2–1.3 × 0.7–0.8 mm, with 2 inconspicuous rows of 3–5 shallow depressions separated by low ridges.

Cyathial

arrangement: terminal pleiochasial branches usually 3, occasionally reduced to congested cyme, 1–2-branched;

pleiochasial bracts 2–4, often whorled, wholly green or paler green, white, or mauve at base, similar in shape and size to distal leaves or slightly narrower;

dichasial bracts similar in shape to distal leaves but smaller (often highly reduced).

Cyathia

peduncle 0.7–1 mm.

in dense, usually terminal, capitate glomerules, with reduced, bractlike leaves subtending cyathia;

peduncle 0.8–2.3 mm.

2n

= 28.

Euphorbia dentata

Euphorbia lasiocarpa

Phenology Flowering and fruiting spring–fall. Flowering and fruiting year-round.
Habitat Bottomland forests, stream and river banks, bluffs, prairies, glades, fallow fields, roadsides, railroad cinders, open disturbed areas. Open disturbed areas, mostly along roadsides and railroad tracks.
Elevation 0–1000 m. (0–3300 ft.) 0–10 m. (0–0 ft.)
Distribution
from FNA
AL; AR; GA; IA; IL; IN; KS; KY; LA; MD; MI; MO; MS; NC; NE; OH; OK; PA; SC; TN; TX; VA; WV; ON; Mexico (Chihuahua, Coahuila, Nuevo León, Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
from FNA
FL; Mexico; Central America; South America; West Indies [Introduced in North America]
[BONAP county map]
Discussion

Euphorbia dentata is native from northern Mexico and the south central United States north and east through the Ohio River Valley. Scattered occurrences in the southeastern United States likely represent adventive populations. Reports of E. dentata as a noxious weed (from the United States and the Old World) should most likely be attributed to introductions of E. davidii.

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

Euphorbia lasiocarpa is similar to E. hypericifolia but is much more hairy on its stems and leaves. Euphorbia lasiocarpa is widespread throughout tropical America, but its precise native range in the New World is not clear. In the flora area, E. lasiocarpa is found in southern Florida, where it is likely introduced.

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

Source FNA vol. 12, p. 321. FNA vol. 12, p. 275.
Parent taxa Euphorbiaceae > Euphorbia > sect. Poinsettia 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. 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. 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 dentata Chamaesyce lasiocarpa
Name authority Michaux: Fl. Bor.-Amer. 2: 211. (1803) Klotzsch: Nov. Actorum Acad. Caes. Leop.-Carol. Nat. Cur. 19(suppl. 1): 414. (1843)
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