Leaves dimorphic, 45--100 × 12--20 cm; fertile leaves dying back in winter; sterile leaves 1--several, smaller, green through winter. Petiole 1/4--1/3 length of leaf, scaly at least at base; scales scattered, tan, sometimes with dark brown center. Blade green, lanceolate, with nearly parallel sides, pinnate-pinnatifid, herbaceous, not glandular. Pinnae of fertile leaves twisted out of plane of blade but not fully perpendicular to it, narrowly elongate-deltate; basal pinnae narrowly elongate-deltate, much reduced; basal pinnules longer than or equal to adjacent pinnules, basal basiscopic pinnule and basal acroscopic pinnule equal; pinnule margins serrate or biserrate, with spiny teeth. Sori midway between midvein and margin of segments. Indusia lacking glands. 2 n = 246. Swampy woods; 50--600 m; N.B., Ont., Que.; Conn., Ind., Maine, Mass., Mich., N.H., N.J., N.Y., Ohio, Pa., R.I., Vt. Dryopteris clintoniana is a North American endemic and an allohexaploid derived from D . cristata and D . goldiana . Dryopteris clintoniana hybridizes with six species. Hybrids can be identified by the fairly narrow blades and elongate-deltate proximal pinnae.

Sterile and fertile lvs similar or only slightly different, evergreen, to 13 dm; petiole to 3.5 dm, scaly at the base, the scales ovate, ca 1 cm, concolorous or with darker brown center; blade lanceolate, commonly 1.5-2 dm wide, pinnate-pinnatifid, ±acuminate; pinnae mostly 10-18 pairs, the larger ones mostly 7-11 נ2-4 cm, short-petiolulate, lance-oblong, acuminate, the 10-15 pairs of segments oblong, 10-23 נ6-9 mm, obtuse, incurved-serrate or biserrate, the teeth subspinulose; veins 5-7 pairs per segment; basal pinnae relatively short and broad-based, mostly 1.5-2.5 times as long as wide; 2n=246, thought to be an alloploid of nos. 3 [Dryopteris cristata (L.) A. Gray] and 5 [Dryopteris goldiana (Hook.) A. Gray]. Swamps and wet woods; Me. and Que. to Wis., s. to N.Y., n. N.J., n. Pa., n. O., and n. Ind.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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