Coelophragmus auriculatus (A. Gray) O. E. Schulz in Engler, Pflanzenreich IV. 105(Heft 86): 157. 1924; Sisymbrium auriculatum A. Gray, Smithsonian Contrib. Knowl. 3: 8. 1852. TYPE: United States, Texas, valley of a stream about 10 miles from the Rio Grande, below El Paso, 3 Sep 1949,C. Wright 9 (lectotypes designated by Payson (1922: 25), GH!; isolectotypes, GH!, US!).

Thelypodium lobatum Brandegee, Univ. Calif. Publ. Bot. 4: 178. 1911; Coelophragmus auriculatus var. lobatus (Brandegee) O. E. Schulz in Engler, Pflanzenreich IV. 105(Heft 86): 158. 1924. TYPE: Mexico, Coahuila, Sierra de Parras, Oct 1910, C. A. Purpus 4561 (holotype, UC!; isotypes, GH!, MO!, US!).

Herbs, annual, sparsely to densely pilose at least below. Stems (2–)3–12(–15) dm, erect, simple or often several branched above. Basal leaves not rosulate, soon withered; lower and middle cauline leaves pinnatifid to runcinate; petiole 1–6 cm, auriculate to amplexicaul at base; leaf blade oblanceolate to obovate in outline, (2–)3–12(–17) × (1.5–)2.5–6(–8.5) cm, lateral lobes ovate to lanceolate, terminal lobe larger than lateral ones; uppermost cauline leaves short petiolate, gradually reduced in size and lobing upward. Racemes densely flowered; fruiting pedicels horizontal, 0.5–1 (–1.4) cm, stout, straight or slightly curved upward, glabrous or pubescent. Sepals oblong, 4–5 × 1–1.5 mm, sparsely pilose; petals white to lavender, spatulate, 6–10 × 1.5–2.5 mm, gradually narrowed to a claw-like base; filaments of median stamens 2.5–4 mm; anthers narrowly oblong, 1–1.5 mm; ovules 78–120 per ovary. Fruit linear, 2–4.2(–5.3) cm × 0.5–0.7 mm, straight; style 0.5–2.5 mm. Seeds yellowish, ovate, 0.4–0.5 × 0.3–0.4 mm.

Flowering: Mar–Nov.

Habitat: hillsides, shallow washes, calcareous grounds, thickets, scrubby woodland of pines and oaks, gravelly flats.

Elevation: 1200–2400 m.

Distribution: Mexico (Coahuila, Chihuahua, Durango, Nuevo León, San Luis Potosí, Zacatecas), United States (SW Texas).