Syst. Bot. 16: 656. 1991.
Herbs, annual, (0.6–)1–4.3 dm; with fibrous roots. Stems solitary or few, erect, unbranched, sometimes branched, hairs spreading, short and long, soft and stiff, eglandular. Leaves green to purplish, linear to linear-lanceolate, (0.8–)2–6(–8.7) cm, not fleshy, margins plane, flat, 3–5-lobed, apex acuminate; lobes ascending, linear to narrowly lanceolate, long, apex acuminate to rounded. Inflorescences 5–25 (longer in fruit) × 1–2 cm; bracts proximally greenish to dull reddish brown, distally pink, lavender, magenta, purple-red, or white on apices, narrowly lanceolate, (3–)5-lobed; lobes ascending, linear to narrowly lanceolate with slightly widened apices, medium length to long, arising near or below mid length, apex acute. Calyces colored as bracts, sometimes proximally yellow, 15–20 mm; abaxial and adaxial clefts 7–9.5 mm, abaxial ca. 33% of calyx length, adaxial ca. 66% of calyx length, deeper than laterals, lateral 3–5.5 mm, 33% of calyx length; lobes ± linear, slender, all 4 similar, apex acute. Corollas straight, 15–30 mm; tube 14–23 mm, not expanded distally, majority of it exserted from calyx; beak straight, adaxially white or pink (drying purple), 4–6 mm, pubescent; abaxial lip ± inconspicuous, exserted, pouches 3, 2 mm wide, 1–1.5 mm deep, 3–5 mm, 50–70% as long as beak, white, yellow, or pink with large deep purple, red, or brown spot on each pouch at or extending below middle; teeth erect, white, yellow, or pink, 1–1.5 mm. Filaments glabrous. 2n = 48.
Phenology: Flowering Mar–Jun.
Habitat: Arid grasslands in hilly country, sagebrush or alkaline flats.
Elevation: 50–1200 m.
Castilleja brevistyla is endemic to the foothills of the southern Sierra Nevada and the southern reaches of the Inner South Coast Ranges, in Kern and adjacent counties. It often grows with other annuals, including C. attenuata, C. densiflora, and C. exserta. The similar C. attenuata has three-lobed bracts and leaves, while C. brevistyla has mostly five-lobed parts, and also differs in corolla structure and spotting. Hybrids between C. brevistyla and C. exserta are known from Kern County.