Man. Fl. Pl. Calif., 919. 1925.
Subshrubs or shrubs. Stems erect to ascending, 500–1200 (–1500) mm, minutely hirtellous-hirsutulous and minutely stipitate-glandular. Leaves usually cauline, relatively even-sized; petiole absent or indistinct; blade narrowly oblong to narrowly elliptic-lanceolate proximally to lanceolate to elliptic-lanceolate or elliptic distally, 15–60 (–75) × 2–20 mm, margins entire or shallowly serrate, plane or revolute, apex obtuse to rounded, surfaces glabrous or abaxial sparsely to densely hairy, hairs branched, adaxial usually without unbranched hairs. Pedicels 4–13 mm in fruit. Flowers 2 (–4) per node, chasmogamous. Calyces not inflated in fruit, 18–30 mm, glabrous or minutely hirtellous and/or minutely stipitate-glandular, tube slightly dilated distally, lobes subequal to unequal, apex acute, ribs green, intercostal areas light green. Corollas yellow-orange to orange, not spotted or striped, palate ridges yellow to golden yellow or orange, tube-throat 25–30 mm, limb 20–30 mm diam., bilabiate to nearly rotate, lobes oblong, apex of adaxial 2 each shallowly, asymmetrically incised. Anthers exserted (at throat), glabrous. Styles sparsely glandular. Stigmas exserted, lobes equal. Capsules 18–31 mm. 2n = 20.
Phenology: Flowering Apr–Aug.
Habitat: Sand dunes and bluffs, dry hillsides, grassy slopes, road banks, stream banks, basaltic knolls, rocky slopes and outcrops, open pine forests, coastal scrub.
Elevation: 0–700(–1000) m.
Diplacus aurantiacus occurs from southwestern Oregon (Curry County) southward to Santa Barbara County, California.