Phytoneuron 2013-21: 2, figs. 1–6, 10. 2013.
Herbs, perennial, 0.5–19 dm; from a branching, woody caudex; with a taproot. Stems few-to-many, short-decumbent, becoming upright-ascending, unbranched, hairs moderately dense, spreading to erect, medium length and long, soft, mixed with shorter stipitate-glandular ones. Leaves greenish to dull purplish brown, linear to linear-lanceolate or narrowly lanceolate or narrowly oblong, 1–7 cm, not fleshy, margins plane, involute, (0–) 3-lobed, apex acute, distalmost obtuse to rounded; lobes erect, linear-lanceolate to narrowly long-triangular, usually shorter and narrower than central lobe, usually arising at or above mid length, apex acute to rounded. Inflorescences 2.5–8 × 2–5 (–8) cm at midflowering; bracts red to red-orange, crimson, or magenta throughout, sometimes green, pale orange, rose red, salmon, or yellow throughout, or proximally greenish or dull reddish, distally colored as above, lanceolate to elliptic or oblong, 3 (–5) -lobed; lobes ascending to erect, linear to lanceolate or narrowly oblong, short or medium length, arising near or above mid length, central lobe apex rounded to acute, lateral ones acute to obtuse. Calyces colored as bracts, 24–44 mm; abaxial and adaxial clefts 9–18 mm, 30–45% of calyx length, deeper than laterals, lateral 1–4 mm, 5–10% of calyx length; lobes lanceolate to ovate, apex rounded to acute. Corollas straight or slightly curved, 24–45 (–50) mm; tube 22–38 mm; beak and abaxial lips conspicuously exserted; beak adaxially green to yellow, 8–11 mm; abaxial lip ascending, green, sometimes yellowish or black, slightly inflated, visible through front cleft and subequal to calyx, 4–6.5 mm, 33–50% as long as beak; teeth ascending, pink, white, or rose red, 1–4 mm.
Phenology: Flowering Jul–Aug(–Sep).
Habitat: Moist to dry, rocky or gravelly slopes and ridges, scree, talus, krummholz, turf or fellfields, snowfield or meltwater margins, subalpine to alpine, Cambrian limestone.
Elevation: 2100–2900 m.
Castilleja kerryana is endemic to alpine peaks and ridges around the Scapegoat Plateau of Lewis and Clark County, in the eastern Rocky Mountains of central-western Montana. It is closely associated with and probably parasitic on Dryas hookeriana.
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