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pillpod sandmat, pillpod spurge

San Pedro River sandmat

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

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

erect to ascending, 10–55 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.

opposite;

stipules distinct, narrowly triangular and often divided into 3–5 subulate to filiform segments, 0.8–1.9 mm, glabrous;

petiole 1.2–3.1 mm, glabrous;

blade oblong, elliptic, or ovate, 12–43 × 3–14 mm, base subsymmetric to asymmetric, rounded, attenuate, or with one side hemicordate and other side rounded, margins usually serrulate, rarely entire on some leaves or portion of blade, apex obtuse to acute, surfaces often with red blotch in center, glabrous; pinnately veined, often only midvein conspicuous.

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.

oblong, campanulate, or funnel-shaped, 1.5–2.6 × 1.1–2.3 mm, glabrous;

glands 4, green to yellowish or tinged with red, subcircular to oblong, 0.4–0.7 × 0.5–1 mm;

appendages absent or white, often forming narrow rim or oblong to ovate, 0–0.8 × 1.2 mm, distal margin entire.

Staminate flowers

2–8.

50–60.

Pistillate flowers

ovary strigillose, often canescent when young;

styles 0.2–0.6 mm, 2-fid 1/2 length.

ovary glabrous;

styles 0.5–0.6 mm, 2-fid 1/2 length.

Capsules

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

columella 0.7–1 mm.

oblate, 2.4–3.2 × 3–3.5 mm, glabrous;

columella 2.3–2.5 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.

light brown, ovoid, 4-angled in cross section, abaxial keel well developed, 1.9–2.3 × 1.3–1.4 mm, finely dimpled and papillate.

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.

solitary at distal nodes;

peduncle 1.4–2.4 mm.

Euphorbia hirta

Euphorbia trachysperma

Phenology Flowering and fruiting year-round. Flowering and fruiting late summer–early winter.
Habitat Disturbed areas, roadsides, vacant lots, desert grasslands, mesquite woodlands, riparian forests with cottonwoods and willows, flood plain forests, pinelands, deciduous forests. Desert scrub, desert grasslands, mesquite woodlands.
Elevation 0–1500 m. (0–4900 ft.) 200–1200 m. (700–3900 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
AZ; Mexico (Baja California Sur, Sonora)
[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 trachysperma may be expected in extreme southwestern New Mexico given the close proximity of some collections in southeastern Arizona.

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

Source FNA vol. 12, p. 271. FNA vol. 12, p. 291.
Parent taxa Euphorbiaceae > Euphorbia > sect. Anisophyllum 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. 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. trichotoma, E. vallis-mortae, E. velleriflora, E. vermiculata, E. villifera, E. virgata, E. wrightii, E. yaquiana
Synonyms Chamaesyce gemella, C. hirta, E. gemella Chamaesyce trachysperma
Name authority Linnaeus: Sp. Pl. 1: 454. (1753) Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 189. (1859)
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