Stems short-creeping. Petiole dark red-brown at base, straw-colored distally, 10--45 cm, swollen, with 2 rows of teeth; scales at base light brown, linear-lanceolate to lanceolate. Blade oblong-lanceolate, pinnate-pinnatifid, 30--80 × 12--25(--30) cm, narrowed to base, broadest near middle, acuminate at apex. Pinnae linear-oblong, base truncate, apex acuminate; segments oblong, margins entire to slightly lobed, apex round to slightly pointed. Costae and veins with multicellular hairs. Veins pinnate, lateral veins simple or 1-forked. Sori elongate, straight or hooked; indusia ± thick, margin ± entire. 2 n = 80. Damp woods, often on slopes; 30--1500 m; N.B., N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., Ga., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis. Deparia acrostichoides belongs to sect. Lunathyrium . Closely related Asian ferns have been treated as conspecific with Deparia acrostichoides , but D . acrostichoides differs from them in having creeping stems with rather distant leaves and pinnate-pinnatifid leaves. Deparia acrostichoides and Asian species such as D . pycnosora (H. Christ) M. Kato and D . allantodioides (Beddome) M. Kato are examples of vicariant species pairs with amphipacific disjunct distributions.
Rhizome short-creeping, the lvs at the front end, 3.5-11 dm, the blade longer than the petiole, 13-22 cm wide, sharply acuminate, slightly reduced below, pinnate-pinnatifid, the rachis septate-hairy and sparsely scaly, pinnae 15-20 pairs below the pinnatifid tip, deeply pinnatifid, the costal wing 0.5-1 mm wide, the segments oblong, barely to strongly toothed, 6-13 נ3-6 mm; veins simple or forked, directed into the teeth; indusia 3-7 pairs per segment, light brown, firm, elongate, mostly 1.5-2 mm, straight or nearly so, seldom crossing the veins; 2n=80. Rich moist woods; N.S. and N.B. to Ont., and Minn., s. to Ga., La., and Okla. (Asplenium acrostichoides; Diplazium t.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.