Bull. Torrey Bot. Club 100: 83, fig. 1. 1973.
Herbs, perennial, (0.5–) 0.8–1.4 (–1.8) dm; from a woody caudex; with a taproot with yellow root hairs. Stems several, erect, usually decumbent at base, unbranched, sometimes branched, sometimes with short, leafy axillary shoots, hairs spreading, short, rather stiff, some glandular. Leaves purplish brown with a grayish cast (due to adhering soil particles and salt crystals), linear to narrowly lanceolate, 1.5–2.5 (–3) cm, fleshy, margins plane, sometimes wavy, involute, 0–3 (–5) -lobed, apex acute; lobes spreading, linear to narrowly lanceolate, apex obtuse. Inflorescences 3–10 × 1.5–5 cm; bracts proximally purplish, deep burgundy, lavender, dull reddish, or deep purple, distally greenish, white, cream, or pink on margins and apices, oblong, 3 (–5) -lobed; lobes ascending, ± linear, medium length, arising above mid length, central lobe apex rounded to obtuse, expanded distally, lateral ones acute. Calyces proximally whitish, distally purple to sometimes pink, margins white or cream, 16–20 mm; abaxial and adaxial clefts 5–8.5 mm, 20–45% of calyx length, all 4 clefts subequal; lobes linear or narrowly lanceolate, apex obtuse to rounded. Corollas straight or slightly curved, 18–22 (–24) mm; tube 13–18 mm; beak, sometimes abaxial lip, exserted; beak adaxially purplish brown, 4.5–6.5 mm, conspicuously exceeding abaxial lip, margins reddish or colored as bracts, apices white or cream; abaxial lip reddish purple with green in a distal band or along grooves, gradually inflated, grooved, (2–) 3–4 (–4.5) mm, 67% as long as beak; teeth erect to slightly spreading, white to cream, often with purple spot, 1.4–2 (–2.5) mm. Stigmas blackish. 2n = 24.
Phenology: Flowering Jun–Jul.
Habitat: Damp alkaline clay, hummocks, sparsely vegetated stream banks draining hot springs.
Elevation: 1800–2000 m.
Castilleja salsuginosa is endemic to a single site in White Pine County, where it is limited to the harsh alkaline soils of travertine hot springs. This population is threatened by habitat degradation from livestock, as well as by water developments affecting the hydrology of the hot spring system. Castilleja salsuginosa is closely related to C. nana and C. pilosa, but genetic studies of the trio are inconclusive so far. Two populations of very similar but slightly smaller-flowered plants occur around other hot springs in adjacent Eureka County. While they resemble C. salsuginosa superficially, recent morphometric studies of one of these populations indicate that they may be worthy of nomenclatural recognition, separate from C. salsuginosa.
Castilleja salsuginosa is in the Center for Plant Conservation’s National Collection of Endangered Plants.
"medium" is not a number.