Edward B. Knobel

“ Compare general shapes, stems, and points with drawings on the black-ground plates; also lower leaflets with detail drawings in regard to veins, sawteeth, points, and fruit dots.
The drawings are all about one-third natural size.
Key to Ferns (Filices) .
Stem not forked.
The Ferns have been classified by their fruit, which consists of minute one-celled powder-like spores in a case (sporangium) . The sporangia are often clustered into round or oblong dots (sori) , and these are sometimes covered by a thin skin (indusium) . ”

“ Spleenwort. Asplenium thelypteroides. 11⁄2 to 21⁄2 ft.; fruit dots oblong, divisions not as crowded as in No. 17, stem leafy to ground, veins simple.
16. Common Meadow Fern. Aspidium thelypteris. 2 ft.; bare long stalk, fruit dots round and crowded, veins forked.
17. Common Wood Fern. Aspidium noveboracense. 1 to 2 ft.; fruit dots round, leaflets crowded, stem leafy to ground, veins simple. ”

“ There are several varieties, one smaller with only short sawtoothed leaflets, one larger with long curved leaflets.
28. Bladder Fern. Cystopteris bulbifera. 1 to 2 ft.; slender, sometimes little bulblets on stems. ”