Key to Wisconsin Cystopteris

• 1a.Blades triangular, widest at or near base, attenuate at apex; bulblets often present on upper part of rachis; most or all veins ending in tiny notches; small gland-tipped hairs usually present on rachis and indusia (except in C. tennesseensis); plants often on calcareous rocks 2

• 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 4

• 2a.Most blades (except those emerging in spring) narrowly triangular, apex long-attenuate, often bearing globose bulblets; young petioles reddish; all veins ending in notches between lobes C. bulbifera

• 2b.Blades triangular to narrowly ovate, apex short-attenuate, often with a few deformed bulblets; petioles brown to yellow-green; some veins ending in teeth 3

• 3a.Blades narrowly ovate to lanceolate, the longest pinnae usually third or fourth above the base; gland-tipped hairs sparse; scales on rhizome dark brown C. laurentiana

• 3b.Blades narrowly triangular, widest at the lowest or second lowest pair of pinnae; gland tipped hairs usually lacking; scales on rhizome tan C. tennesseensis

• 4a.Stems protruding 1--4 cm beyond the leaves, covered with golden hairs; petioles pale green to straw-colored at base; usually growing on forest soil C. protrusa

• 4b.Stems scarcely protruding beyond leaves, lacking hairs; petioles brown at the base; often growing on cliff faces 5

• 5a.Pinnae with shallow rounded teeth; pinnules of lowest pinnae often cuneate at base; many veins ending in notches; pinnae often at acute angle to rachis and curved toward apex C. tenuis

• 5b.Pinnae with sharp teeth; pinnules of lowest pinnae rounded to truncate at base; nearly all veins ending in pointed teeth; pinnae perpendicular to rachis and not curved toward apex C. fragilis