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smallseed sandmat

Paria spurge, Utah spurge

Habit Herbs, annual, with slender little-branched taproot.
Stems

erect to ascending, branched, dichotomous distally and slightly angled, 4–25 cm, glabrous or sparsely strigillose.

Leaves

opposite;

stipules 0.1–0.2 mm;

petiole 2–6 mm, glabrous or sparsely strigillose;

blade usually linear- to narrowly-elliptic, occasionally ovate to obovate, 14–42 × 3–10 mm, progressively narrower distally, base attenuate, margins entire, apex usually acute, rarely obtuse, surfaces glabrous or sparsely strigillose;

venation inconspicuous.

Involucre

campanulate, 1–1.1 × 1.2–1.4 mm, strigillose at least toward apex;

glands 5, green-yellow, oblong, 0.4–0.6 × 0.7–1 mm;

appendages whitish to yellow-green, lunate to broadly ovate, 0.2–0.5 × 0.7–1.1 mm, entire or slightly crenulate.

Staminate flowers

25–30.

Pistillate flowers

ovary glabrous;

styles 0.7–1 mm, 2-fid at apex.

Capsules

oblate to subglobose, 2.9–3.2 × 3.2–3.4 mm, glabrous;

columella 2.8–3.1 mm.

Seeds

light gray to whitish, oblong-ovoid, rounded in cross section, 2.3–2.6 × 1.3–1.5 mm, dimpled and rugulose;

caruncle absent.

Euphorbia

polycarpa is a highly variable species distributed throughout the Baja California peninsula, eastern Sonora, and the arid southwestern United States from southwestern Arizona to southern Nevada and central California.

l

.

c

.

Wheeler

(1941) divided the species into seven varieties, the majority of which occur in Baja California Sur.

He

reported two of these for the United States: var. hirtella and var. polycarpa.

Variety

hirtella, as the name suggests, was applied to hairy plants.

However

, it is here treated as a synonym of var. polycarpa, because variation in pubescence shows no geographic segregation and ranges along a continuum from glabrous or sparsely to densely hairy, and because glabrous and hairy branches can occur on the same individual.

Cyathia

solitary at distal bifurcations of stems;

peduncle 0.6–2.4 mm, glabrous or strigillose.

Euphorbia polycarpa

Euphorbia nephradenia

Phenology Flowering and fruiting spring–summer.
Habitat Saltbush, blackbrush, Ephedra-dominated scrub and desert communities.
Elevation 1100–1500 m. (3600–4900 ft.)
Distribution
from FNA
AZ; CA; NV; nw Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; UT
[BONAP county map]
Discussion

Varieties 5 (1 in the flora).

Some of the varieties occurring in Mexico are highly divergent and appear to be sufficiently distinct to merit recognition as species. However, within the flora area, Euphorbia polycarpa is relatively uniform, and the only noteworthy variation involves the size of the involucral gland appendages. In the portion of the California Floristic Province occupied by E. polycarpa (Los Angeles, Orange, western Riverside, western San Diego, and Ventura counties) the appendages are conspicuously larger than those of plants throughout the remainder of its range in the southwestern United States (0.4–1.2 versus 0.1–0.3 mm). Large-appendaged plants are also common in Baja California and correspond well with the type collection. The taxonomic significance of this variation is not clear at this time, and the small-appendaged plants may merit segregation as an infraspecific taxon. However, no formal changes are proposed, awaiting a comprehensive review of the species throughout its range.

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

Euphorbia nephradenia is the only species of the genus endemic to the Colorado Plateau of Utah and adjacent Colorado.

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

Source FNA vol. 12, p. 283. FNA vol. 12, p. 249.
Parent taxa Euphorbiaceae > Euphorbia > sect. Anisophyllum Euphorbiaceae > Euphorbia > sect. Alectoroctonum
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. 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. 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
Subordinate taxa
E. polycarpa var. polycarpa
Synonyms Chamaesyce polycarpa
Name authority Bentham: Bot. Voy. Sulphur, 50. (1844) Barneby: Leafl. W. Bot. 10: 314. (1966)
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