Herbs, perennial, 1.5–5.5(–7.5) dm; from a woody caudex; with a taproot. Stems several to many, erect or ascending, often grayish, unbranched or often branched distally, glabrate proximally or hairy, especially distally, rarely glabrous, hairs sparse, spreading to appressed, usually curly, ± short, soft, sometimes mixed with sparse, short stipitate-glandular ones. Leaves often grayish or purplish, linear to narrowly lanceolate or narrowly oblong, (1–)2.5–5(–6.7) cm, not fleshy, margins plane or wavy, involute, deeply (0–)3–5(–7)-lobed, apex acute to acuminate; lobes divaricate to spreading or ascending, linear, arising at or below mid length, apex acute to acuminate. Inflorescences 3.5–20(–29) × 1–4 cm; bracts pale green to pale yellow throughout, or proximally pale green to pale yellow, distally pale yellow to bright yellow, sometimes light orange, light red, or bright red, lanceolate to narrowly oblong or narrowly elliptic, slightly broader than leaves, usually 3–5-lobed; lobes ± spreading, linear or narrowly lanceolate, short or long, proximal or all bracts arising near or below mid length, apex acute, sometimes narrowly obtuse. Calyces proximally green, sometimes purple or pinkish, distally yellow to light orange, dull green, or colored as bracts, 11–28 mm; abaxial and adaxial clefts 4–16(–17) mm, 30–60(–95)% of calyx length, deeper than laterals, lateral 0.5–7 mm, 4–30% of calyx length; lobes linear to lanceolate or narrowly to broadly triangular, apex acute to acuminate. Corollas straight or ± curved, 13–30 mm; tube 12–16 mm; beak, sometimes abaxial lip, slightly to strongly exserted, corolla often curved and exserted through abaxial cleft; beak adaxially green, (5–)6–12 mm; abaxial lip green or yellow, reduced, exserted or more commonly visible in cleft in calyx, 1–3.5 mm, 20–33(–50)% as long as beak; teeth ascending, green to yellow, 0.5–2 mm. 2n = 48.
Colo., Idaho, Mont., Nev., Oreg., Utah, Wyo.
Varieties 2 (2 in the flora).
Both varieties of Castilleja flava are characteristic plants of sagebrush-dominated communities throughout its wide range, from valleys to moderate elevations in the mountains, sometimes reaching the lower subalpine. The species almost always occurs in close association with shrubby species of Artemisia.
|1||Corolla beaks 5–12 mm, abaxial lips 1–2 mm; calyx abaxial clefts 8–16 mm, adaxial 4–8(–15.5) mm; n Great Basin, c Rocky Mountains.||Castilleja flava var. flava|
|1||Corolla beaks 5–8(–9.5) mm, abaxial lips (1.5–)2–3.5 mm; calyx abaxial and adaxial clefts subequal, (6–)7–13(–17) mm; mountains of ne Oregon to c Idaho.||Castilleja flava var. rustica|