Proc. Amer. Acad. Arts 19: 93. 1883. (as Castilleia)
Herbs, perennial, 0.5–3 dm; from a woody caudex; with a taproot. Stems several to many, erect to ascending, or decumbent, inflorescence erect in high-elevation form, unbranched, sometimes branched, hairs dense, spreading, ashy gray, short and long, soft, mixed with short stipitate-glandular ones. Leaves green, brown, purple, or deep gray, linear or narrowly to broadly lanceolate to sometimes ovate, 0.7–3 cm, not fleshy, margins plane, slightly involute, 0(–3)-lobed, apex acuminate; lobes ascending to spreading, linear to lanceolate, apex acuminate. Inflorescences 1–8.5 × 2–5 cm; bracts proximally greenish or deep reddish purple, distally burnt orange, sometimes yellow or deep red to deep burgundy, proximal sometimes lanceolate with narrow lobes, distal or all bracts broadly lanceolate to oblong or slightly oblanceolate, (0–)3–5-lobed, appearing dusty with dense, short stipitate-glandular hairs, many with a nodulose to pillarlike, crystallized, usually pigmented exudate, papillose at 40×; lobes ascending-spreading, oblong or oblanceolate, short, arising above mid length, central lobe apex rounded, often expanded, rounded, or truncate, lateral ones acute to rounded. Calyces colored as bracts, sometimes whitish proximally, 1.5–20 mm (shorter in upper elevation form); abaxial and adaxial clefts 3.5–8 mm, 30–50% of calyx length, all 4 clefts subequal; lobes linear to narrowly oblong or oblanceolate, apex obtuse to rounded, densely stipitate-glandular. Corollas straight, 12–18 mm; tube 9–14 mm; beak included or tip just barely exserted, adaxially green or pale yellow to deep burgundy, 3–5 mm; abaxial lip green, burgundy, or reddish purple (in high-elevation form), little inflated, small, included, 2 mm, to 20% as long as beak; teeth incurved, green, 0.2–0.5 mm.
Phenology: Flowering May–Aug(–Oct).
Habitat: Dry rocky slopes, ridges, and flats, pebble plains, sagebrush openings, open conifer forests.
Elevation: 1800–3100 m.
Castilleja cinerea is endemic to the higher elevations of the San Bernardino Mountains, San Bernardino County. Most plants are upright to ascending and have yellow to yellow-orange inflorescences, with occasional plants ranging to dull red, especially with age. On Sugarloaf Mountain, mostly above 2700 m, is a distinctive form with consistently reddish purple to burgundy inflorescences and a strongly decumbent growth form.
Castilleja cinerea is most often associated with and likely parasitic on Artemisia nova and Eriogonum species. Castilleja cinerea is known from few populations and is threatened by livestock grazing, development, and vehicle use. It is listed as a threatened species under the Endangered Species Act of the United States.
The crystalline exudate associated with the stipitate-glandular pubescence of the distal portion of the bracts is unique in the genus.