Leafl. W. Bot. 2: 244. 1940.
Herbs, perennial, 0.8–2.1 dm; from a woody caudex; with slender, branching roots. Stems few-to-many, decumbent-based to erect, unbranched except for short, leafy axillary shoots, hairs sparse, spreading, long, soft, mixed with short-stipitate-glandular ones. Leaves green to purple (sometimes different on stems of same plant), linear-lanceolate, 1–3.5 cm, not fleshy, margins plane, flat, 0 (–3) -lobed, apex acute; lobes spreading-ascending, linear-lanceolate to lanceolate, apex acute. Inflorescences 2–4.5 × 1.5–2 cm; bracts proximally greenish to dull brownish purple, distally pink to magenta or reddish purple, ovate, broadly lanceolate, or oblong, (0–) 3–5-lobed; lobes ascending to erect, lanceolate, medium length, arising near or above mid length, apex acute to rounded. Calyces proximally brown or dull magenta, sometimes green, distally colored as bracts, 11–19 mm; abaxial and adaxial clefts 9–10 mm, 55–60% of calyx length, deeper than laterals, lateral 2.5–5 mm, 15–25% of calyx length; lobes oblong, apex rounded. Corollas straight, 18–20 mm; tube 14–15 mm; abaxial lip sometimes partly exserted, beak usually exserted; beak adaxially white, 7–10 mm, margins white or pale salmon; abaxial lip pale green to yellow-green, inflated, pouches 3, shallow, central pouch shallowly grooved, visible through front cleft, 6–7 mm, 60–70% as long as beak; teeth erect, white, 1–2 mm. Stigmas pale green. 2n = 24.
Phenology: Flowering Jul–Sep.
Habitat: Moist to wet meadows, shorelines, subalpine, volcanic soils.
Elevation: 1500–2500 m.
Castilleja lassenensis is restricted to the Mt. Lassen area in Shasta and Tehama counties. See the discussion of 55. C. lemmonii for information on the relationship between these two species.
"acute" is not a number."medium" is not a number.