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Abrams' sandmat, Abrams' spurge

mountain spurge

Habit Herbs, annual, with slender taproot. Herbs, perennial, with thick rootstock.
Stems

prostrate, mat-forming, 10–35(–50) cm, shortly pilose or puberulent at least proximally, often glabrous distally.

erect, branched, 40–90 cm, glabrous.

Leaves

opposite;

stipules distinct, divided into 5–7 subulate-filiform segments, 0.6–1.1 mm, usually glabrous, rarely pilose;

petiole 0.5–1 mm, glabrous;

blade ovate, elliptic-oblong, or slightly ovate-cordate, 3–11 × 2–5 mm, base asymmetric, truncate to hemicordate, margins serrulate at least toward apex, often entire toward base, apex acute to obtuse, surfaces sometimes with red spot in center, glabrous; usually only the midvein conspicuous.

petiole 0.5–1 mm;

blade elliptic to oblong, 8–20(–40) × 3–6 mm, base truncate, rounded, or attenuate, margins entire, apex obtuse or acute, sometimes slightly mucronate, surfaces glabrous;

venation inconspicuous, only midvein prominent.

Involucre

obconic, 0.5–0.6 × 0.4–0.5 mm, glabrous;

glands 4, yellowish to pink, circular to oblong, 0.1 × 0.1–0.2 mm;

appendages absent, or white to pink, semicircular to broadly ovate, to 0.1 × 0.2 mm, distal margin entire or shallowly lobed.

turbinate or campanulate, 1.5–2.5 × 1.1–1.9 mm, glabrous;

glands 4, crescent-shaped to semicircular, 0.5–0.8 × 1–1.8 mm;

horns usually convergent, 0.2–0.8 mm.

Staminate flowers

3–5.

8–12.

Pistillate flowers

ovary glabrous;

styles 0.1–0.3 mm, 2-fid nearly entire length.

ovary glabrous;

styles 1–1.8 mm, 2-fid.

Capsules

ellipsoid to ovoid, 1.3–1.5 × 1.1–1.5 mm, glabrous;

columella 1–1.3 mm.

depressed-ovoid, 4.3–5 × 5–6 mm, 3-lobed;

cocci rounded, smooth, glabrous;

columella 3.5–4 mm.

Seeds

light gray to light brown, narrowly ovoid to ovoid, 4-angled in cross section, 1–1.2 × 0.6–0.7 mm, with 3–5 prominent transverse ridges that often interrupt abaxial keel.

gray to dark brown, ovoid-oblong, truncate at both ends, 2.6–3.4 × 2–2.6 mm, shallowly pitted to almost smooth;

caruncle conic, 1 × 0.8 mm.

Cyathia

solitary at distal nodes of primary stems or at nodes of short congested axillary branchlets;

peduncle 0.2–0.5 mm.

peduncle 1–3 mm.

Cyathial

arrangement: terminal pleiochasial branches 3–5(–6), each 3–4 times 2-branched;

pleiochasial bracts ovate-lanceolate to slightly subpandurate, similar in size or wider than distal leaves;

dichasial bracts distinct, lanceolate to broadly ovate, base usually truncate to rounded or subcordate, sometimes attenuate, margins entire or slightly crenulate, apex usually obtuse to acute, occasionally acuminate;

axillary cymose branches 2–8.

2n

= 26.

Euphorbia abramsiana

Euphorbia chamaesula

Phenology Flowering and fruiting summer–fall. Flowering and fruiting spring–summer.
Habitat Desert scrub and desert grasslands. Clearings in ponderosa pine forests, montane roadsides, dry streambeds, creek banks, sandy and gravelly soils.
Elevation -40–1400 m. (-100–4600 ft.) 1700–2700 m. (5600–8900 ft.)
Distribution
from FNA
AZ; CA; NM; TX; Mexico (Baja California, Baja California Sur, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; Mexico (Chihuahua, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Euphorbia chamaesula is easily distinguished from other perennial members of subg. Esula in western North America by its larger capsules and the vegetative shoots (without cyathia) that arise from the distal nodes of the stem proximal to the pleiochasia.

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

Source FNA vol. 12, p. 259. FNA vol. 12, p. 300.
Parent taxa Euphorbiaceae > Euphorbia > sect. Anisophyllum Euphorbiaceae > Euphorbia > subg. Esula
Sibling taxa
E. aaron-rossii, 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. 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. 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 abramsiana Tithymalus chamaesula
Name authority L. C. Wheeler: Bull. S. Calif. Acad. Sci. 33: 109. (1934) Boissier: Cent. Euphorb., 38. (1860)
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