Amer. Fern J. 19: 11. 1929.
Trophophore stalk 0–2 mm, 0 to 0.1 times length of trophophore rachis; blade bright shiny green, oblong-deltate, 1–2-pinnate, to 8 × 5 cm, papery. Pinnae to 7 pairs, only slightly ascending, approximate to overlapping, distance between 1st and 2d pinnae not or slightly more than between 2d and 3d pairs, basal pinna pair approximately equal in size and cutting to adjacent pair, obliquely ovate to lanceolate-oblong, to spatulate, deeply and regularly lobed or pinnulate, lobed to tip, margins entire to very shallowly crenate, apex truncate to somewhat acute, venation pinnate. Sporophores 2-pinnate, 1–2 times length of trophophore. 2n =180.
Phenology: Leaves appearing in June to August.
Habitat: Grassy slopes, streambanks, woods
Elevation: 0–2500 m
Alta., B.C., N.W.T., Yukon, Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
Botrychium pinnatum is most commonly associated with B. lanceolatum and B. lunaria. Specimens of B. pinnatum have been misidentified as Botrychium boreale.