Syst. Bot. 5: 83, fig. 17 [center]. 1980.
Herbs or subshrubs, perennial, 1.5–4.5 dm; from a woody caudex; with a taproot. Stems few to several, decumbent to erect, sometimes leaning, unbranched or often much-branched distally, with a few short, leafy axillary shoots, hairs spreading, short, soft, stipitate-glandular, mixed with long-spreading, eglandular ones. Leaves gray-green, sometimes green, lanceolate-linear to narrowly lanceolate, 1–6.5 cm, not fleshy, margins plane, sometimes wavy, flat to involute, 0 (–3) -lobed, apex acuminate; lobes spreading-ascending, linear to narrowly lanceolate, apex acute. Inflorescences 3–30 × 3–4 cm; bracts proximally green to dark purplish, distally red to crimson, sometimes pale salmon, linear-lanceolate to broadly lanceolate, 3–5-lobed; lobes spreading, linear, long, arising below mid length, apex acute, sometimes obtuse. Calyces colored as bracts, 15–20 mm; abaxial clefts 3.4–6.2 mm, adaxial 4.5–9 mm, clefts 25–33% of calyx length, deeper than laterals, lateral 0.5–2 mm, 5–10% of calyx length; lobes narrowly triangular, often slightly unequal, apex acute. Corollas straight or slightly curved, 20–40 mm; tube 15–23 mm; abaxial lip exserted to included, beak much exserted; beak adaxially yellow-green to reddish, 9–18 mm; abaxial lip green, reduced, 0.5–1.5 mm, 5–20% as long as beak; teeth incurved, green, (0–) 0.5–1.5 mm. 2n = 48, 72.
Phenology: Flowering May–Aug.
Habitat: Dry rocky slopes, ledges, open conifer forests, thickets, washes.
Elevation: 1900–2900 m.
Castilleja montigena is endemic to the northeastern portion of the San Bernardino Mountains of southern California. In the field, this species is consistently and relatively easily distinguished from nearby populations of C. martini var. martini, which it essentially replaces in the northeastern portion of the San Bernardino Mountains. It is apparently of allopolyploid hybrid origin between C. martini var. martini and C. chromosa, which approaches its range from the adjacent Mojave Desert.
"acute" is not a number.