Basal pinnules broad-based and mostly sessile or subsessile; indusium to 1 mm, usually cleft at the apex; relatively northern, s. to Mich., Vt., and in the mts. to N.C. (C. dickieana)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.