Proc. Acad. Nat. Sci. Philadelphia 86: 532. 1934.
Herbs, perennial, 0.7–2.6 dm; from a many-headed, short, woody caudex; with a taproot. Stems few, ascending, unbranched, sometimes branched, glabrate to sparsely hairy proximally, becoming densely hairy distally, proximal hairs appressed, white, short, soft, eglandular, distal hairs widely spreading to erect, white or yellowish, long to very long, soft, eglandular. Leaves green to sometimes redbrown or dull purplish, linear to linear-lanceolate, 1.5–4 cm, not fleshy, margins plane, sometimes ± wavy, involute, (0–) 3 (–5) -lobed, apex acute to acuminate; lobes linear or linear-lanceolate, laterals ± divaricate, often abruptly upcurved from plane of main leaf-blade, proximals usually 33–50% as long as leaf, apex acuminate to acute. Inflorescences 2–11 × 1–2.5 cm; bracts greenish or pale-yellow, rarely purplish or deep red, often with dull purplish veins on proximal bracts, or proximally greenish or pale-yellow, distally whitish, yellow, or orange-yellow, proximal sometimes linear-lanceolate, distal broadly lanceolate to oblong or obovate, (0–) 3–5 (–7) -lobed; lobes ascending to erect, linear to lanceolate, short to medium length, arising above mid length, proximal bract apex acute, distal obtuse, rounded, or truncate. Calyces colored as bracts, proximally often paler, usually yellow throughout, 10–20 mm; abaxial and adaxial clefts 7–14 mm, 40–50% of calyx length, deeper than laterals, lateral 0.5–1.5 mm, 5–15% of calyx length; lobes triangular, apex acute to rounded. Corollas slightly curved, 10–22 mm; tube 8–14 mm; teeth of abaxial lip sometimes slightly exserted, beak exserted or subequal; beak adaxially green to pale-yellow, 5–8 mm; abaxial lip deep yellow or green, reduced, forming a small pouch visible through front cleft, 3–5 mm, 50–75% as long as beak; teeth ascending to erect, white or yellow, 1 mm. 2n = 24.
Phenology: Flowering May–Aug(–Sep).
Habitat: Dry to mesic rocky tundra, slopes, ridges, barrens and meadows, openings in boreal forests, arctic to alpine.
Elevation: 0–2200 m.
B.C., N.W.T., Yukon, Alaska, e Asia (Russian Far East)
Castilleja hyperborea is widespread across boreal, alpine, and arctic habitats in western Canada and Alaska, extending into the Russian Far East. A rare form with light purple bracts was named as C. kuschei. Another form with particularly long hairs found in the Kluane Lake region of the southern Yukon was described as C. villosissima and is usually found on calcareous substrates.
"arising" is not a number.