Key to Wisconsin Gymnocarpium

• 1a.Lowest pair of pinnae nearly as long as the terminal (main) division of the blade, the blade about as wide as long; rachis and midveins on underside of pinnae glabrous; blades thin and membranous G. dryopteris

• 1b.Blades ovate to narrowly lanceolate or elliptical, widest near middle, usually acute at apex; bulblets not produced; most or all veins ending in teeth (except many ending in notches in C. tenuis); tiny gland-tipped hairs lacking; plants often growing on forest soil or cliff faces 2

• 2a.Blades rank-smelling, glandular on the upper surface, especially on the midveins of the pinnae; lowest pair of pinnae diverging almost perpendicular to the rachis; second pair of pinnae usually with a short stalk G. robertianum

• 2b.Blades glabrous on upper surface; lowest pair of pinnae and lower pinnules curving upward toward blade apex; second pair of pinnae sessile G. jessoense