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bristlecup sandmat

saw tooth spurge, saw-tooth or tooth or serrate spurge, serrate spurge

Habit Herbs, perennial, with woody, thickened taproot. Herbs, perennial, with thick rootstock.
Stems

usually erect, rarely slightly decumbent, often densely clustered from top of woody crown, 3–15 cm, glabrous.

erect, branched, 10–70 cm, glabrous.

Leaves

opposite;

stipules distinct, narrowly linear, usually entire, 0.5–1 mm, glabrous;

petiole 0.5–1 mm, glabrous;

blade ovate to lanceolate or oblong- or linear-lanceolate, 3–11 × 0.8–3(–5) mm, base slightly asymmetric, short-tapered, occasionally one side slightly rounded, margins entire, apex acute or short-acuminate, surfaces glabrous;

only midvein conspicuous.

petiole absent;

blade lanceolate, ovate-lanceolate, linear, or linear-lanceolate, 10–70 × 2–20 mm, base acute or obtuse, margins irregularly serrate, apex acute to obtuse, surfaces glabrous;

venation inconspicuous, only midvein prominent.

Involucre

campanulate to turbinate, 0.8–1.4 × 0.8–1 mm, glabrous;

glands 4, yellow-brown to reddish, concave or convex, elliptic or oval, 0.2–0.4 × 0.4–0.6 mm;

appendages absent or white, lanceolate-deltate to straplike, 0.2–1.1 × 0.2–0.9 mm, distal margin entire, crenate, or deeply cleft or divided.

campanulate, 2–4 × 1.2–3 mm, glabrous;

glands 4–5, elliptic, ovate, or suborbiculate, 1.2–1.8 × 1.5–2.7 mm;

horns absent or slightly divergent, 0–0.6 mm.

Staminate flowers

25–35.

20–40.

Pistillate flowers

ovary glabrous;

styles 0.3–0.4 mm, 2-fid 1/2 length.

ovary glabrous;

styles 1–2 mm, 2-fid.

Capsules

depressed-ovoid to depressed-globose, 1.7–2.1 × 1.6–2.4 mm, glabrous;

columella 1.2–1.8 mm.

subovoid, 4.5–6 × 4–5 mm, 3-lobed;

cocci rounded, smooth occasionally slightly puncticulate, glabrous;

columella 4–4.5 mm.

Seeds

white, ovoid-pyramidal, prominently 4-angled in cross section, 1.6–2 × 1–1.2 mm, smooth to slightly wrinkled.

grayish, cylindric, 2.5–3.1 × 1.7–2 mm, smooth or slightly dotted;

caruncle subconic, lobed, 1–1.5 × 0.5–1 mm.

Cyathia

solitary at distal nodes;

peduncle 0.8–1.3 mm.

peduncle 1–5 mm.

Cyathial

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

pleiochasial bracts ovate-lanceolate, usually shorter and wider than distal leaves;

dichasial bracts distinct, ovate or deltate, base obtuse to cordate, margins irregularly dentate, apex acute, or obtuse, mucronate;

axillary cymose branches 0–3.

Euphorbia chaetocalyx

Euphorbia serrata

Phenology Flowering and fruiting spring–fall.
Habitat Waste places, disturbed sites, roadsides, fields, pastures.
Elevation 0–300 m. (0–1000 ft.)
Distribution
from FNA
AZ; NM; TX; n Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Europe; Atlantic Islands (Macaronesia) [Introduced in North America]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

Euphorbia chaetocalyx is similar to E. fendleri but can generally be distinguished from that species by its narrow, acute leaves and ± erect stems. Some authors have used the presence or absence and shape of the involucral gland appendages to help separate E. chaetocalyx from E. fendleri, but those characters appear highly variable and of little taxonomic utility. Some individuals from western Texas (Culberson and El Paso counties) and southern New Mexico appear intermediate with E. fendleri. The specific epithet of E. chaetocalyx refers to the bristly perianthlike segments that subtend the ovary, but these structures are found intermittently in both E. chaetocalyx and E. fendleri.

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

Euphorbia serrata, native to the western Mediterranean region of Europe and Macaronesia, is listed as a noxious weed by the state of California. In the flora area, it has been found in coastal counties from Sonoma to Monterey counties; attempts to eradicate it may have been successful.

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

Key
1. Leaf blades ovate to lanceolate or oblong- or linear-lanceolate; involucral gland appendages absent or lanceolate-deltate, entire, crenate, or deeply cleft; widely distributed in Arizona, New Mexico, w Texas.
var. chaetocalyx
1. Leaf blades narrowly-ovate to linear-lanceolate; involucral gland appendages straplike, divided into 3–5 linear segments; cliffs and rocks of Boquillas Canyon, sw Texas.
var. triligulata
Source FNA vol. 12, p. 263. FNA vol. 12, p. 309.
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. 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. 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. 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. chaetocalyx var. chaetocalyx, E. chaetocalyx var. triligulata
Synonyms E. fendleri var. chaetocalyx, Chamaesyce chaetocalyx Galarhoeus serratus, Tithymalus serratus
Name authority (Boissier) Tidestrom: Proc. Biol. Soc. Wash. 48: 40. (1935) Linnaeus: Sp. Pl. 1: 459. (1753)
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