Proceedings of the Ohio State Academy of Science. 2^3 



SUBKINGDOM. PTERIDOPHYTA HOMOSPORAE. 



Homosporous Pteridophytes ; 4,500 known living species. 



Plants in which the herbaceous or tree-like sporophyte, after 

 the juvenile stage, has an independent existence with true fibro- 

 vascular tissue, roots, and leaves, and with a terminal growing 

 point ; homosporous and either eusporangiate or leptosporangiate. 

 Gametophyte usually rather large, normally hermaphrodite al- 

 though often unisexual ; thalloid and green but sometimes tu- 

 berous and subterranean and without chlorophyll. 



Class J. FiLiCES. Ferns. About 4,000 living species. 



Sporophyte herbaceous or tree-like, usually with a horizontal 

 rhizome, simple or branched ; leaves usually large, alternate and 

 mostly compound, rarely slender and grass-like; sporangia borne 

 on the under side of the leaves or on simple or branched sporan- 

 giophores ; eusporangiate or leptosporangiate ; sporophylls not 

 forming cones. Gametophyte comparatively large, tuber-like 

 without chlorophyll and subterranean, or commonly developed 

 as a flat, simple or branched thallus, hermaphrodite or unisexual ; 

 spermatozoids multiciliate. 



KEY TO THE GENERA OF OHIO FILICES. 



Required for identitication — perfect leaves with the entire 

 petioles, some of the leaves with sporangia which need not, how- 

 ever, be mature. The vascular bundles should be determined 

 at or very near the base of the petiole. The number following 

 the ger.eric name refers to the list number. 



1 . Leaf blades areolatc, the veins anastomosing to form a network. 2. 



1 . Leaf blades not areolate, the veins not anastomosing, but dicho- 



tomous or pinnate, and ending free. 5. 



2. Leaf blades simple, entire, with a distinct sporangioijluirc with two 



rows of sporangia, vascular bundles in petiole 3-G 



Ophioi^lossuni (1). 



