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



SUBKINGDOM, PTERIDOPHYTA HOMOSPORAE. 

 Homosporoiis 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- 

 A'-ascular 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 I. 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 identification — 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 generic name refers to the list number. 



1. Leaf blades areolate, 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 sporangiophore with two 



rows of sporangia, vascular bundles in petiole 3-6 



Opliioglossuui (1). 



