Flora of North America species comparison

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Euphorbia hirta

Euphorbia virgata

pillpod sandmat, pillpod spurge

leafy spurge, slender leafy spurge, Wolf's milk
Habit Herbs, annual or perennial, with slender to thickened taproot. Herbs, perennial, with slender, spreading rootstock.
Stems

usually erect to ascending, rarely prostrate or decumbent, 10–50(–75) cm, usually both strigillose and hirsute.

erect, unbranched or branched, 20–90 cm, glabrous.
Leaves

opposite;

stipules usually distinct, rarely connate at base, undivided or divided into 2–4 narrowly deltate to linear-subulate segments, 0.5–1.8(–2.9) mm, pilose, often with light-colored, minute circular glands at base;

petiole 1–3 mm, usually both strigillose and hirsute;

blade ovate to rhombic, 7–43 × 3–18 mm, base strongly asymmetric, one side rounded or slightly cordate to truncate, the other cuneate to attenuate, margins serrulate to double serrulate, apex acute, surfaces often with red spot in center, usually strigose to hirtellous, rarely glabrescent; 3–5-veined from base.

petiole 0–1 mm;

blade linear to linear-oblanceolate or linear-oblong (margins parallel or almost parallel at midleaf), 40–90 × 3–12 mm, base truncate or abruptly attenuate, margins entire, apex acute or rounded, sometimes mucronulate, surfaces glabrous;

venation inconspicuous, only midvein prominent.
Involucre

obconic, 0.6–1.2 × 0.4–0.9 mm, strigillose;

glands 4, greenish to pink, circular, oblong, or reniform, 0.1–0.2 × 0.1–0.2 mm;

appendages white to pink, flabellate, subcircular, or transversely oblong, rarely absent, (0–)0.1–0.6 × (0–)0.1–0.7 mm, distal margin usually entire, rarely slightly lobed.

campanulate, 1.5–3.5 × 1.7–3 mm, glabrous;

glands 4, crescent-shaped, 0.6–1.5 × 1.3–2.5 mm;

horns divergent to convergent, 0.2–0.8 mm.
Staminate flowers

2–8.

10–25.
Pistillate flowers

ovary strigillose, often canescent when young;

styles 0.2–0.6 mm, 2-fid 1/2 length.

ovary glabrous;

styles 1.7–2.5 mm, 2-fid.
Capsules

subglobose to slightly oblate, 1–1.3 × 1.1–1.6 mm, strigillose;

columella 0.7–1 mm.

subglobose, 2.5–3.5 × 3–4.5 mm, slightly lobed;

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

columella 2–3.3 mm.
Seeds

brownish red to orange or pink, narrowly ovoid, 4-angled in cross section, 0.7–0.9 × 0.5–0.7 mm, usually rugulose or with 3–6 low transverse ridges, rarely nearly smooth.

yellow-brown to gray or mottled, oblong-ellipsoid to oblong-ovoid, 2.2–2.6 × 1.3–1.6 mm, smooth;

caruncle subconic, 0.6–1 × 0.7–0.9 mm.
Cyathia

in dense, axillary and terminal, capitate glomerules, with reduced, bractlike leaves subtending cyathia, axillary glomerules either sessile or at tips of elongated, leafless stalks;

peduncle 0.4–2.1 mm.

peduncle 0–1 mm.
Cyathial

arrangement: terminal pleiochasial branches 5–17, each 1–2 times 2-branched;

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

dichasial bracts distinct, broadly ovate, rhombic, or reniform, base cordate or cuneate, margins entire, apex obtuse to rounded, mucronulate;

axillary cymose branches 0–18.
2n

= 60.

Euphorbia hirta

Euphorbia virgata
Phenology Flowering and fruiting year-round. Flowering and fruiting spring–fall.
Habitat Disturbed areas, roadsides, vacant lots, desert grasslands, mesquite woodlands, riparian forests with cottonwoods and willows, flood plain forests, pinelands, deciduous forests. Pastures, fields, waste places, shorelines, railroads, open disturbed areas.
Elevation 0–1500 m. (0–4900 ft.) 0–2600 m. (0–8500 ft.)
Distribution
from FNA
AL; AR; AZ; CA; FL; GA; LA; MS; NC; NM; NY; SC; TX; Mexico; Central America; South America; West Indies; Bermuda [Introduced in North America; introduced also in Europe, Asia, Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AZ; CA; CO; CT; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; ND; NE; NH; NJ; NM; NV; NY; OH; OR; PA; SD; UT; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; ON; PE; QC; SK; YT; Europe; Asia [Introduced in North America]
[BONAP county map]
Discussion

Euphorbia hirta is a widespread weed that is distributed throughout tropical and subtropical regions of the world. It is probably native to at least central Mexico, and its native range possibly extends from South America to the southern United States. In many places within the flora area the species is certainly introduced, and it has been recorded as a waif from several states (for example, Maryland, Michigan, and Virginia). Euphorbia pilulifera Linnaeus, a rejected name that is a heterotypic synonym of the Asian E. parviflora Linnaeus, has been misapplied to North American material of E. hirta in the past.

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

Euphorbia virgata has caused significant economic and ecological impact over large portions of the United States and Canada. It is part of a taxonomically complex group of species native to Europe and Asia, and there has been much confusion over the naming of the species that has become widely established in the New World (A. Radcliffe-Smith 1985; P. M. Catling and G. Mitrow 2012). There has been speculation that hybridization and polyploidy have played a role in the weediness of leafy spurge, and it is possible that the widespread occurrence of leafy spurge in North America is at least partly due to multiple introductions in grain imported from Eurasia (Ma J. S. 2010). Nonetheless, a re-evaluation of the leafy spurge complex by Berry et al. (unpubl.) revealed that E. esula Linnaeus and E. virgata are two distinct, albeit related species. The true E. esula is restricted in range to certain parts of Europe and shows little tendency toward weediness where it occurs. In contrast, E. virgata is much more widespread across Europe and temperate Asia, where it shows the same weedy characteristics as leafy spurge in the New World. More importantly, it is morphologically consistent with the North American material of leafy spurge.

According to D. V. Geltman (1998), the best way to distinguish morphologically between Euphorbia virgata and E. esula is by differences in their leaf shape. In E. virgata, the leaf blades are linear to linear-oblanceolate or linear-oblong, 6–15 times longer than wide, with margins that are parallel or almost parallel at the middle of the blade; the apex is usually acute, and the base is truncate or abruptly attenuate. In E. esula, the leaf blades are oblanceolate to obovate-elliptic (distinctly wider toward apex), 3–8(–10) times longer than wide, with margins not parallel at the middle of the leaf; the apex is rounded to subacute, and the base is gradually attenuate to cuneate.

There are some herbarium specimens of Euphorbia esula from North America that indicate it probably occurred sporadically in certain states in the late 1800s and early 1900s, but the authors have no evidence that it has persisted in any of those places. Therefore in this treatment, E. esula is considered to be a waif in the North American flora and, by excluding it here, the authors hope to avoid confusion between it and the widespread E. virgata.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 271. FNA vol. 12, p. 312.
Parent taxa Euphorbiaceae > Euphorbia > sect. Anisophyllum 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. 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. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. wrightii, E. yaquiana
Synonyms Chamaesyce gemella, C. hirta, E. gemella
Name authority Linnaeus: Sp. Pl. 1: 454. (1753) Waldstein & Kitaibel: Descr. Icon. Pl. Hung. 2: 176, plate 162. (1803)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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