Stems few to several, (1-)2-6 (-7.5) dm, densely pubescent. Basal leaves: petiole (0.7-)1.5-5 (-7) cm; blade obovate to spatulate or broadly oblong, (1-)2-8(-10) cm × (5-)10-40 (-60) mm, base cuneate to truncate, apex acute to subobtuse, surfaces densely pubescent. Cauline leaves shortly petiolate or (distalmost) sessile; blade similar to basal, 1-5.5(-6.5) cm × 5-25(-40) mm (smaller distally). Racemes 0.5-4 cm. Fruiting pedicels usually straight or upcurved, rarely slightly sigmoid, (4-)5-15(-20) mm. Flowers: sepals (4-)5-8 × 1.5-2 mm; petals (7-)8-11(-13) × (5-)6-9 mm, claw to 2 mm; filaments 4-6 mm; anthers 2.5-4 mm, (base strongly sagittate). Fruits (0.7-)0.8-1.2(-1.5) cm × 5-8(-9) mm, apex deeply notched; valves densely pubescent; style 2-5 mm. Seeds 1.5-2 × 1.2-1.7 mm. 2n = 20.

Flowering Oct-May. Creosote bush-mesquite scrubland, grasslands, gravelly hillsides, rocky sandstone or limestone slopes, rocky flats, limestone rubble, gypsum of llano, calcareous gravel, sandy or loamy areas; 50-2400 m; Tex.; Mexico (Chihuahua, Coahuila, Durango, Hidalgo, Nuevo León, San Luis Potosí, Tamaulipas, Zacatecas).

Synthlipsis greggii is known from Brewster, Hidalgo, and Zapata counties.