Trophophore stalk 0--1 mm; blade dull to shiny green to dark green, deltate, 1--2-pinnate, to 6 × 7 cm. Pinnae to 5 pairs, ascending, approximate, distance between 1st and 2d pinnae not or slightly more than between 2d and 3d pairs, linear to broadly lanceolate, entire to divided to tip, margins with distinct lobes or segments, apex acute to rounded, venation pinnate. Sporophores 1--3-pinnate, 1--2.5 times length of trophophore, divided into several equally long branches (all other botrychiums have a single stalk or 1 dominant and 2 smaller). 2 n =90.
Plants 6-40 cm, wholly glabrous; blade and sporophore reflexed in bud; blade supramedial, dark green, deciduous, sessile or with a short stalk to 6 mm, deltoid, mostly 1-6 נ1-9 cm, with 2-5 pairs of ±pinnatifid pinnae, the lowest pair of pinnae much the largest, the pinnae and pinnules mostly longer than wide; sporophore 1.5-9 cm, mostly bipinnate, its stalk mostly (0.5-)1-3 cm, surpassed by the blade; 2n=90. Circumboreal, s. in Amer. to Va., W.Va., O., Minn., Colo., and Wash. July-Aug. Var. lanceolatum, a stout, fleshy plant with the lobes of the pinnae 1-5 mm wide, broad-based, and apically rounded, is a subarctic and boreal plant of mt. slopes and meadows, s. to n. Me. (B. hesperium) Var. angustisegmentum Pease & A. H. Moore, a laxer and more membranous plant with the lobes of the pinnae 1-2.5 mm wide, rather distant, narrow at the base and apically acute, occurs in moist, shady woods and margins of swamps from Nf. to Ont. and Wis., s. to Va., W.Va., and O.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.