Fl. Aleut. Isl., 300, plate 14. 1937.
Plants 4–30 cm. Leaves: basal 0–2, blade elliptic, 1–10 x 1–5 mm, 1-pinnatifid, margins of adjacent lobes nonoverlapping or slightly overlapping distally, dentate, surfaces glabrous; cauline 0–5, blade lanceolate or elliptic to deltate, 7–30 x 1–25 mm, 1-pinnatifid or 2-pinnatifid, margins of adjacent lobes nonoverlapping or slightly overlapping distally, serrate, surfaces glabrous. Racemes simple or paniculate, 1–3, exceeding basal leaves, each 8–20-flowered; bracts deltate, 5–20 x 10–15 mm, 1-pinnatifid or 2-pinnatifid nearly to midrib, lobes sometimes laciniate, margins serrate, surfaces glabrous. Pedicels 1–1.5 mm. Flowers: calyx 3.5–8.5 mm, glabrous, lobes 2 (–4), triangular, 2–6 mm, apex dentate to 2-dentate, glabrous; corolla 8–16 mm, tube light pink to purple, 5–9 mm; galea bicolored, yellow with purple spots proximally, purple distally, 3–6.5 mm, beakless, margins 1-toothed medially and distally, apex straight to arching slightly over abaxial lip; abaxial lip yellow to pink with purple spots, 3–8 mm. 2n = 16 (Asia).
Phenology: Flowering Jun–Aug.
Habitat: Moist tundras, stream banks, wet terraces, willow thickets, wet meadows, fens, bogs.
Elevation: 0–500 m.
B.C., Alaska, Asia
Pedicularis palustris and P. pennellii are extensively branched, with branching in P. pennellii more compact and subequal, making it appear shrubby. The branches of P. palustris, in contrast, become progressively shorter distally on the stem, giving the plant a pyramidal appearance.
Calder and Taylor recognized subsp. insularis by its smaller or sometimes absent apical teeth on the galea margins. Boivin subsequently reduced it to a variety. Given this minor difference, this taxon (found only on Haida Gwaii [the Queen Charlotte Islands] of British Columbia) is not recognized here.