Procccdijigs of the Ohio State .■^cadciiiy of Science. 271 



Classes, Filices, 



Hyclro]iteri(les, 

 Isoeteae. 



2. Cahiiiiofhyla. 25 known living- >i)C'cies. Vascular seed- 

 less plants with jointed stems and small whorled leaves with 

 comparatively large multiciliate sperms, and with the sporophylls 

 in cones. 



Classes, Equiseteae. 



S]Dhenophylleae ( Fossil ) , 

 Calaniarieae (Fossil). 



3. LefidofJiyta. (\()0 known living s])ecies. Vascular seed- 

 less plants with simple, usually small leaves covering- the stem, 

 with small biciliate sperms, and with the sporophylls in cones 

 or somctinies forming zones alternating- with the sterile leaves. 



Classes, Lycopodieae. 

 Selaginelleae. 



KEY TO THE CLASSES OF HOMOSPOROUS AND 

 HETEROSPOROUS PTERIDOPHYTES OF OHIO. 



1 . With cuniparaliNcl}- large, broad, compound or rarely simple, abun- 

 dantly veined k-aves ; homosporous. the spores all of one kind ; 

 sporangia borne fMi the foliage leaves or on special sporangio- 

 phores I. Filices. Ferns. 



]. W'itli 4-fnliate. slender-petioled leaves from a horizontal rhizome; 

 or small, free-floating plants with small ■2-ranked foliage leaves ; 

 heterosporous, the spores of two sizes, microspores and megaspores ; 

 sporangia in sporocarps IV. Hydropterides. Water- ferns. 



1. Leaves small, short, and scale-like, scattered or in whorls; or long, 

 grass-like, and in a rosette; plants not floating; homosporous or 

 heterosporous. 2. 



:2. With minute scale-like leaves in a whorl, forming sheaths at the 

 nodes of the jointed stem; homosporous, the spores with append- 

 ages, the peltate sporophylls in cones 



IT. FnuiSETE.-XE. Horsetails and Scouring Rushes. 



