Rep. U.S. Mex. Bound. 2(1): 190. 1859.
Herbs, annual, with slender, fibrous taproot. Stems erect, 20–70 cm, glabrous or with few scattered spreading hairs; branches arcuate, branching appearing dichotomous. Leaves usually alternate, occasionally opposite at proximalmost node; petiole 15–49 mm, glabrous; blade usually ovate, rarely oblong or elliptic, 13–54 × 7–38 mm, base usually rounded to broadly cuneate, rarely truncate, margins finely serrulate, apex obtuse, surfaces glabrous or with few scattered hairs; venation pinnate, midvein prominent. Cyathial arrangement: terminal dichasial branches 2, few-branched (weakly defined); pleiochasial bracts 2–3, opposite or whorled, wholly green, similar in shape and size to distal leaves; dichasial bracts smaller than distal leaves, often white at base. Cyathia: peduncle 0.9–3.5 (–6.2) mm. Involucre tubular or obconic, 1–1.7 × 0.7–1.4 mm, glabrous except for few hairs on lobes; involucral lobes divided into several linear, smooth lobes; glands 1 (–3), greenish, sessile and broadly attached, 0.3–0.4 × 0.4–0.8 mm, opening oblong to subcircular, glabrous; appendages petaloid, white, elliptic, oblong, transversely oblong, or forming thin, lunate rim on gland margin, not incurved and covering glands, 0.3–0.9 × 0.6–1.3 mm, entire, undulate or slightly lobed, glabrous. Staminate flowers 20–30. Pistillate flowers: ovary glabrous; styles 0.6–1 mm, 2-fid 1/2 length. Capsules oblate, 2.8–3.1 × 3.6–4.5 mm, glabrous; columella 1.9–2.4 mm. Seeds brown to blackish, ovoid, rounded in cross-section, 1.9–2.4 × 1.5–1.8 mm, irregularly and coarsely tuberculate; caruncle absent or rudimentary.
Phenology: Flowering and fruiting summer–fall.
Habitat: Riparian areas with cottonwoods and willows, pinyon pine woodlands, pine-oak forests, Douglas fir forests with pines.
Elevation: 1900–2300 m.
N.Mex., Tex., Mexico, Central America (Guatemala)
Euphorbia bifurcata is found in the mountains of southern New Mexico (Doña Ana, Grant, Lincoln, Otero, and Sierra counties) and trans-Pecos Texas (Brewster, Jeff Davis, and Presidio counties).
"thin" is not a number.