Prelim. Cat. 3. 1888
Habitat: Forest floor or on rocks, often invading masonry and disturbed soils
Elevation: 0–1300 m
Ont., Que., Ala., Ark., Ariz., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.Mex., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis., s Africa.
The combining author for Asplenium platyneuron is often given as Oakes ex D. C. Eaton; see D. B. Lellinger (1981) for justification of the authorship employed here.
Asplenium platyneuron is remarkable in that it occurs in southern Africa as well as in North America. No other North American fern has this distribution. Asplenium platyneuron is an ecological generalist and is particularly characteristic of disturbed woodlands. This species is migrating northward on the northern portions of its range in the upper Great Lake states (W. H. Wagner Jr. and D. M. Johnson 1981). Proliferous buds on the lowest pinnae allow formation of clumps with stems at several layers in the litter. Asplenium platyneuron hybridizes with A. rhizophyllum, A. trichomanes (producing A. × virginicum Maxon), A. pinnatifidum, A. ruta-muraria (producing A. × morganii W. H. Wagner & F. S. Wagner), A. bradleyi, and A. montanum (producing sterile A. bradleyi).