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Arizona sandmat, Arizona spurge

sand-dune sandmat or spurge

Habit Herbs, annual or short-lived perennial, with slender to slightly thickened taproot. Herbs, annual, with taproot.
Stems

erect to ascending, 10–30 cm, uniformly pilose with glistening hairs.

prostrate, spreading and lanky or occasionally mat-forming, ± succulent, 70–150 cm, glabrous.

Leaves

opposite;

stipules distinct, deltate, (0–)0.1 mm, glabrous or with few scattered hairs;

petiole 0.4–1.5 mm, pilose with glistening hairs;

blade usually ovate, rarely elliptic, 3–11 × 2–7 mm, base asymmetric, one side cuneate to rounded, other side rounded to strongly cordate, margins entire, apex obtuse or acute, surfaces pilose with glistening hairs; 3-veined from base but usually only midvein conspicuous.

opposite;

stipules usually distinct, occasionally connate basally (primarily at distal nodes), usually divided into 2–5 subulate to subulate-filiform segments, occasionally forming narrow deltate segments (primarily at distal nodes), 0.8–1.8 mm, glabrous;

petiole 3.1–6.3 mm, glabrous;

blade ovate to elliptic-oblong, 5–26 × 4–12 mm, base subsymmetric to symmetric, rounded to cuneate, margins entire, apex usually mucronate, rarely acute or obtuse, surfaces glabrous; pinnately veined.

Involucre

urceolate, 1.1–1.3 × 0.5–0.9 mm, glabrous or pilose with glistening hairs;

glands 4, dark maroon, usually oblong to reniform, rarely almost circular, 0.2 × 0.2–0.4 mm;

appendages white to pink, oblong, flabellate, oblong, or elliptic, 0.3–0.6 × 0.6–0.9 mm, distal margin entire or crenulate.

campanulate, 1.1–1.8 × 1.5–2.5 mm, glabrous;

glands 4, yellowish, sessile or short stipitate, circular to oblong, 0.5–0.7 × 0.5–0.8 mm;

appendages white to yellowish, ovate to oblong, occasionally rudimentary, (0–)0.8–1.2 × 0.8–1.5 mm, distal margin entire.

Staminate flowers

5–12.

15–25.

Pistillate flowers

ovary pilose, styles 0.5–0.6 mm, 2-fid 1/2 length.

ovary glabrous;

styles 0.7–1 mm, 2-fid 1/2 length.

Capsules

broadly ovoid to subglobose, 1.4–1.8 mm diam., pilose;

columella 1.1–1.4 mm.

ovoid, 4.7–5.5(–6) × 3.6–5.1 mm, glabrous;

columella 4.3–5.1 mm.

Seeds

gray to light brown, ovoid, 4-angled in cross section, 0.9–1.1 × 0.5–0.6 mm, rugose with 2–5 irregular transverse ridges that sometimes pass through abaxial keel.

grayish white to reddish brown mottled, bottle-shaped, strongly dorsiventrally compressed and weakly 3-angled in cross section, (2.8–)4.1–5.2 × 1.2–2(–3.4) mm, smooth; carunclelike structure linear, 0.4–0.5 × 0.1–0.2 mm.

Cyathia

solitary at distal nodes;

peduncle 0.7–3.6 mm.

solitary at distal nodes;

peduncle 1.4–3.6 mm.

Euphorbia arizonica

Euphorbia carunculata

Phenology Flowering and fruiting year-round in response to sufficient moisture. Flowering and fruiting summer–fall.
Habitat Washes and rocky slopes, sometimes on limestone, desert scrub communities often with creosote-bush, riparian forests, mesquite woodlands, oak chaparral. Sand dunes.
Elevation 100–1400 m. (300–4600 ft.) 400–1300 m. (1300–4300 ft.)
Distribution
from FNA
AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
KS; NM; OK; TX; Mexico (Chihuahua)
[BONAP county map]
Discussion

Euphorbia arizonica is distinctive and easily recognized by its glistening, translucent hairs that appear somewhat glutinous and are most apparent on the stems.

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

Euphorbia carunculata has a highly localized and scattered distribution. The species is restricted to sand dunes and known from only a handful of localities throughout its relatively wide range. The seeds are unique in being bottle-shaped and strongly laterally compressed, and unlike other members of sect. Anisophyllum, there is a minute, linear, carunclelike protuberance at the hilum.

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

Source FNA vol. 12, p. 260. FNA vol. 12, p. 262.
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. 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. 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. 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
Synonyms Chamaesyce arizonica Chamaesyce carunculata
Name authority Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 186. (1859) Waterfall: Rhodora 50: 63. (1948)
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