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Habit Herbs, annual, with taproot.
Stems

erect, usually branched near base, 6–22 cm, glabrous.

Leaves

petiole absent;

blade linear to slightly lanceolate or linear-oblanceolate, 5–18 × 0.5–2.5 mm, base linear attenuate, margins entire, apex rounded to obtuse or acute, surfaces glabrous;

venation pinnate, midvein prominent.

Involucre

infundibular, 0.8–1.1 × 0.6–0.9 mm, glabrous;

glands 4, crescent-shaped; 0.2–0.4 × 0.5–0.6 mm;

horns divergent, 0.5–0.7 mm.

Staminate flowers

5–10.

Pistillate flowers

ovary glabrous;

styles 0.3–0.5 mm, 2-fid.

Capsules

ovoid-globose, 1.8–2.2 × 3–3.2 mm, slightly 3-lobed;

cocci rounded, smooth, glabrous;

columella 1.5–2 mm.

Seeds

white to gray, ellipsoid, 1.4–1.7 × 1–1.3 mm, with deep, irregular to rounded, shallow to concave depressions over entire surface;

caruncle reniform-ovate, depressed-conic, 0.5–0.7 × 0.7–1 mm.

Cyathial

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

pleiochasial bracts similar in shape to but slightly shorter and wider than distal leaves;

dichasial bracts distinct, not imbricate, reniform-ovate to subdeltate-ovate or broadly ovate-lanceolate, base obliquely truncate to rounded, margins entire, apex obtuse to broadly acuminate;

axillary cymose branches 0–3.

Cyathia

peduncle 0–0.5 mm.

Euphorbia austrotexana

Distribution
from FNA
TX
Discussion

Varieties 2 (2 in the flora).

Euphorbia austrotexana occurs in stabilized sandy soil in the south Texas plains (M. H. Mayfield 2013). It is similar to E. longicruris but differs from that species in its often narrowly oblanceolate to linear leaves and its white to gray, ellipsoid seeds that are covered with minute, concave depressions.

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

Key
1. Stems 10–22 cm; leaf blades linear-oblanceolate, apices rounded; dichasial bracts reniform-ovate to subdeltate-ovate, bases truncate; seeds 1.6–1.7 × 1.1–1.3 mm, surfaces with regular concave depressions; Atascosa, Bexar, Wilson counties.
var. austrotexana
1. Stems 6–13 cm; leaf blades linear to slightly lanceolate, apices acute; dichasial bracts broadly ovate-lanceolate, bases rounded; seeds 1.4–1.5 × 1–1.1 mm, surfaces with irregular, not obviously concave depressions; Jim Hogg, Kenedy counties.
var. carrii
Source FNA vol. 12, p. 298.
Parent taxa 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. 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
Subordinate taxa
E. austrotexana var. austrotexana, E. austrotexana var. carrii
Name authority Mayfield: J. Bot. Res. Inst. Texas 7: 634, figs. 1, 2[row 3, left & center]. (2013)
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