Herbs, perennial, sometimes biennial, 1–4.1(–5.5) dm; from a woody caudex; with a taproot. Stems few to many, erect or ascending, unbranched or branched, glabrate proximally or hairy, hairs usually spreading to weakly appressed, whitish or yellowish, short to long, stiff to ± soft, eglandular to rarely stipitate-glandular. Leaves green to red-brown or deep purple, linear-lanceolate to lanceolate or linear, (1.5–)5–10.5 cm, not fleshy, margins plane, sometimes ± wavy, flat to involute, 0-lobed, sometimes 3–5-lobed distally immediately below inflorescence, apex acuminate, caudate, or acute, sometimes obtuse; lobes ascending-spreading, linear to narrowly lanceolate, sometimes with earlike appendages, short, apex acute to obtuse. Inflorescences 2–16 × 1–2.5 cm; bracts yellow, yellow-green, or pale whitish throughout, sometimes with dull reddish-purplish wash proximally, especially with age, proximal few lanceolate, most broadly lanceolate to ovate or lanceolate to oblong, 0–5(–7)-lobed, sometimes central lobe with a few small teeth; lobes ascending to erect, linear, sometimes expanded distally, short, arising near or above mid length, central lobe apex obtuse to rounded or truncate, lateral ones acute to obtuse. Calyces proximally pale green, red-brown, or purple, distally colored as bracts, 12–18.5 mm; abaxial clefts 6–9 mm, adaxial 6–12.1 mm, clefts 45–60% of calyx length, deeper than laterals, lateral 0.3–4(–7) mm, 2–40% of calyx length; lobes linear or triangular to ovoid, apex acute to obtuse or rounded. Corollas straight or slightly curved, 12–26(–28) mm; tube 10–20 mm; abaxial lip sometimes exserted, beak usually exserted; beak adaxially green to yellowish, 3.5–8 mm; abaxial lip proximally green or purple, distally white, purple, yellow to greenish yellow, cream, orange-brown, or reddish, ± inconspicuous, slightly to moderately pouched, 3–6 mm, 50–75% as long as beak; teeth erect to curved, white, cream, or yellow, (0.8–)1.2–2 mm. 2n = 48, 72.
N.W.T., Nunavut, Yukon, Alaska, n Asia.
Varieties 6 (2 in the flora).
Castilleja pallida as interpreted here is one of the most wide-ranging species in the genus, extending from the Kola Peninsula of the western Palearctic eastward across arctic and boreal Asia to similar latitudes in the western Nearctic region. Accounts of this species in the eastern Nearctic and farther south in North America are here attributed to C. septentrionalis, which the authors regard as a separate species. Throughout its enormous range, C. pallida is extremely complex, with several levels of polyploidy documented and numerous localized races of highly variable and inconstant forms. On the other hand, some plants from as far west as the arctic Ural Mountains are virtually identical in morphology to plants of var. caudata in central Alaska. Castilleja pallida is treated differently in regional floras, as one highly variable species or as a complex of numerous species, with or without infraspecific taxa. Despite some recent collections, C. pallida remains an incompletely known entity, and a fairly conservative approach to its delimitation is preferred until its variations and relationships to closely related species such as C. elegans and C. raupii, as well as to the numerous named forms in the Palearctic, are understood. Access to critical type material from Russian herbaria remains problematic as well. A full examination of types and a comprehensive genetic and morphological survey of specimens across the range are needed for a satisfactory treatment of the C. pallida complex.
Only vars. caudata and yukonis in North America are accepted tentatively here, yet it is possible that var. pallida or another east-Asian form occurs in the general area of Nome, Alaska. Some collections from northwestern Alaska appear to be distinct from var. caudata, but their precise identity is not established. Even the morphological boundaries between vars. caudata and yukonis are problematic and variable, especially in the Kluane Lake region of the southern Yukon and adjacent Alaska, as well as in other regions where the two come in contact. The type of Castilleja annua consists of poor material, and the description is based on plastic traits, so here it is treated as a synonym of var. caudata. However, additional research may yield better characters and a rationale to distinguish it.
|1||Lateral calyx clefts (1.5–)3–4(–7) mm, lobes linear, sometimes triangular; leaves lanceolate to linear-lanceolate, rarely linear; stems glabrate or hairy.||Castilleja pallida var. caudata|
|1||Lateral calyx clefts 0.3–2(–4) mm, lobes triangular to ovoid; leaves linear to linear-lanceolate; stems hairy.||Castilleja pallida var. yukonis|