Annuals; glabrous throughout. Stems (simple from base), usually branched distally, 2-7 dm. Basal leaves subrosulate; petiolate; blade oblanceolate, 2.5-20 cm, margins runcinate-pinnatifid. Cauline leaves (petiolate); blade oblanceolate, 4-20 cm × 10-70 mm, (smaller distally), base not auriculate, margins runcinate-pinnatifid (undivided, usually entire distally). Racemes ebracteate, (lax). Fruiting pedicels divaricate-ascending, (5-)10-27 mm. Flowers (strongly zygomorphic); calyx campanulate; sepals (ascending), dark purple, 8-12 mm, not keeled; petals lavender to purple-lavender, (in 2 unequal pairs), abaxial pair undifferentiated into blade and claw, 5-6 mm, margins crisped, adaxial pair 15-26 mm, (not crisped), claw 7-11 mm, crisped, narrower than blade; stamens in 3 unequal pairs; filaments distinct: abaxial pair 6-7 mm, lateral pair 3-5 mm, adaxial pair 8-12 mm; anthers: abaxial and lateral pairs fertile, 4-5 mm, adaxial pair fertile, 3-3.5 mm; gynophore 0.2-0.5 mm. Fruits ascending, smooth, straight, strongly flattened, 3.2-7.5 cm × 4-5 mm; valves each with prominent midvein; replum straight; ovules 30-46 per ovary; style 0.2-0.5 mm; stigma 2-lobed. Seeds orbicular, 3-4 mm diam.; wing 0.5-1 mm wide, continuous.

Flowering Feb-Apr. Talus slopes, rocky hillsides, gravelly and dry stream beds, sand flats, limestone slopes, open scrub or woodland; of conservation concern; 400-700 m; Tex.; Mexico (Coahuila).

In Texas, Streptanthus cutleri is restricted to the Big Bend area in Brewster County.