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mat spurge, narrow-seed spurge, slimseed sandmat

hairy Mojave spurge

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

prostrate, often mat-forming, occasionally with ascending tips, 5–45 cm, densely and evenly pilose to lanate.

slender, erect or ascending, sometimes sinuous, densely branched near base, 10–50 cm, moderately to densely puberulent to lanulose.

Leaves

opposite;

stipules distinct or connate basally on one side of stem, entire or irregularly toothed or fringed, 0.5–1.2 mm, pilose to lanate;

petiole 0.3–1.5 mm, pilose to lanate;

blade usually oblong to oblong-obovate, occasionally nearly circular, 3–10(–15) × 2–5(–10) mm, base asymmetric, one side usually angled or rounded and other truncate-auriculate, margins minutely or conspicuously serrulate at least toward apex, apex usually broadly rounded to broadly acute, occasionally emarginate, abaxial surface often ± lighter green and without reddish spot, both surfaces sparsely to moderately pilose to lanate; 3-veined from base or venation obscure.

petiole 0–1 mm;

blade usually lanceolate or elliptic-lanceolate, sometimes slightly oblanceolate, 8–30 × 6–14 mm, base usually acute, occasionally short-attenuate, rarely obtuse, margins entire, apex usually acute, occasionally obtuse, acuminate, or cuspidate, surfaces sparsely to moderately puberulent to lanulose;

venation pinnate, sometimes obscure, midvein prominent.

Involucre

obconic, 0.7–1 × 0.4–0.6 mm, moderately to densely pilose to lanate;

glands 4, reddish, ± unequal, oblong, 0.1 × 0.1–0.3 mm;

appendages white to strongly pinkish or reddish tinged, often unequal, sometimes 1 to all absent, 0–0.3 × 0–0.4 mm, 3-lobed or rudimentarily 1-lobed, distal margin crenate.

campanulate to broadly turbinate, 2.2–3 × 2–2.5 mm, puberulent to lanulose;

glands 4, semicircular, trapezoidal, or elliptic-truncate, 0.8–1.5 × 1–2.2 mm, margins strongly crenate or dentate;

horns usually absent, if present then straight, 0.1–0.2 mm, generally equaling teeth on gland margin.

Staminate flowers

3–9.

12–20.

Pistillate flowers

ovary pilose to villous, hairs occasionally slightly appressed;

styles 0.2–0.5 mm, unbranched or inconspicuously notched at tip.

ovary usually puberulent, occasionally lanulose;

styles 1–1.2 mm, 2-fid.

Capsules

ovoid, 1.6–2.3 × 1.4–1.5 mm, moderately to densely villous with hairs usually slightly appressed, pubescence often concentrated on proximal 1/2 or along lobes;

columella 1.5–2 mm.

oblong-ovoid, 3.5–4 × 3–4 mm, 3-lobed;

cocci rounded, smooth, usually puberulent, occasionally lanulose;

columella 2.5–3 mm.

Seeds

light to dark brown, usually mottled, sometimes with thin, white coating, often wearing away irregularly, narrowly oblong-ovoid to ellipsoid, 3–4-angled in cross section, 1–1.5 × 0.5–0.6 mm, with short, irregularly interrupted furrows, appearing partially and irregularly few-ridged.

gray to whitish, oblong cylindric, 2–3 × 1.5–1.8 mm, irregularly shallowly pitted to almost smooth;

caruncle conic, 0.6 × 0.6 mm.

Cyathia

solitary at leaf nodes or in small, cymose clusters on congested, axillary branches;

peduncle 0.7–2.5 mm.

peduncle 0.3–0.8 mm.

Cyathial

arrangement: terminal pleiochasial branches 3–5, each 1–2 times 2-branched;

pleiochasial bracts broadly ovate to subcordate, usually similar in size to, occasionally wider than, distal leaves;

dichasial bracts distinct, broadly ovate to almost reniform, base obtuse, margins entire, apex obtuse, acuminate to cuspidate;

axillary cymose branches 0–5.

Euphorbia stictospora

Euphorbia yaquiana

Phenology Flowering and fruiting midsummer–early fall. Flowering and fruiting spring–summer.
Habitat Open disturbed areas, rocky slopes. Ponderosa pine forests, oak-pine mixed forests, dry stream banks and beds, open scrub areas, roadsides.
Elevation 100–2100 m. (300–6900 ft.) 1000–2200 m. (3300–7200 ft.)
Distribution
from FNA
AZ; CO; IA; KS; MO; ND; NE; NM; OK; SD; TX; WY; Mexico (Chihuahua, Durango, San Luis Potosí)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ
[BONAP county map]
Discussion

Euphorbia stictospora has been recorded from New York, but this disjunct occurrence likely represents a waif or misidentification.

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

Euphorbia yaquiana is endemic to Pima and Graham counties in southern Arizona and is known only from the Santa Catalina and Pinaleño mountains. Records of E. yaquiana from southwestern Colorado (as E. incisa var. mollis) likely represent misidentifications of E. brachycera; therefore, those disjunct occurrences have been excluded here from the distribution of E. yaquiana. Euphorbia yaquiana has often been treated as a synonym of E. schizoloba var. mollis, but molecular phylogenetic data show that it is more closely related to E. brachycera and E. chamaesula (J. A. Peirson et al. 2014).

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

Source FNA vol. 12, p. 289. FNA vol. 12, p. 313.
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. 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. 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. virgata, E. wrightii
Synonyms Chamaesyce stictospora E. schizoloba var. mollis, E. incisa var. mollis
Name authority Engelmann: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 187. (1859) Tidestrom: Proc. Biol. Soc. Wash. 48: 41. (1935)
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