Phytoneuron 2015-33: 1, figs. 1–3, 9[left]. 2015.
Herbs, perennial, 1.1–2.8 dm; from a woody caudex; with a taproot. Stems few to many, erect or ascending, short-decumbent at base, unbranched, hairs dense, spreading to erect, ± short, soft, usually stipitate-glandular, longer ones sometimes eglandular. Leaves pale green to dull reddish maroon, linear to linear-lanceolate, 0.8–3.5 cm, not fleshy, margins plane, slightly involute, 0–3(–5)-lobed, apex acuminate; lateral lobes ascending to spreading, linear-lanceolate, usually arising from distal 1/2 of blade, usually narrower than central lobe, apex acuminate to acute. Inflorescences 10–40(–80 with age) × 0.5–2.5 cm; bracts pale cream to pale greenish yellow throughout, often partly to entirely suffused with dull reddish purple to maroon, especially proximally, along veins, and with age, sometimes distal apices pale, dullish red, lanceolate to ovate, usually 3-lobed, central lobe sometimes with short teeth; lobes spreading-ascending, linear-lanceolate, short to medium length, arising at or above mid length, apex acute. Calyces pale cream to pale greenish yellow, sometimes reddish violet to maroon on distal segments and/or with a thin vertical strip of pale reddish violet to maroon along veins, 11–20 mm; abaxial and adaxial clefts 7–12 mm, 60% of calyx length, deeper than laterals, lateral 0.5–1 mm, 5–10% of calyx length; lobes triangular, apex acute to obtuse. Corollas straight, 16.5–25 mm; tube 12–18 mm; beak scarcely exserted, adaxially pale green to yellowish, 3–7 mm; abaxial lip green, not inflated, grooved, 2.5 mm, 33–50% as long as beak; teeth slightly incurved, white, 1 mm.
Phenology: Flowering late Jun–Jul.
Habitat: Hummocks and margins of moist to wet meadows.
Elevation: 1700–1800 m.
Castilleja collegiorum is endemic to a large meadow system in the southern Cascade Range of Klamath County. It is similar to C. cryptantha in Washington and C. lemmonii in California but differs from both in structural details of the inflorescence, calyx, bracts, and leaves.