Subshrubs. Stems erect, 80–330 mm, glabrous. Leaves cauline, relatively even-sized; petiole absent or short; blade narrowly ovate to elliptic-lanceolate, elliptic, or oblanceolate, 20–50 × 3–15 mm, margins dentate to serrate, plane or revolute, apex obtuse to acute, surfaces glabrous. Pedicels 3–10 mm in fruit. Flowers 2 per node, chasmogamous. Calyces inflated in fruit, 35–40 mm, glabrous, tube distinctly dilated distally, lobes subequal, apex acute, ribs green, intercostal areas light green. Corollas pale yellow to cream or nearly white, pale orange, golden yellow, or orange-yellow, not spotted or striped, palate ridges golden yellow, throat internally glabrous, tube-throat 37–52 mm, limb 15–22 mm diam., not bilabiate, lobes entire. Anthers exserted (at throat), glabrous. Styles minutely glandular. Stigmas exserted, lobes equal. Capsules 20–36 mm. 2n = 20.
Phenology: Flowering Apr–Jun.
Habitat: Rock walls, dry rocky soils.
Elevation: 200–1500 m.
Diplacus aridus is known from Imperial and San Diego counties.