Stems moderately to intricately branched; proximal mostly 1-2(-2.5) mm wide. Leaves: basal and proximal cauline blades oblanceolate, 20-40 × 3-8 mm, margins deeply dentate to pinnately lobed.

Flowering Mar-Jun (or sporadically with rain). Open habitats in deep, loose sand, sometimes with oaks; 800-1300 m; N.Mex., Tex.; Mexico (Chihuahua).

Intergrades between var. arenarius and var. robustus occur in Ward and Winkler counties, Texas.