200 The Ohio Naturalist. [Vol. XIV, No. 1, 



((b)). Synangia round, venation reticulate; leaves 

 digitate. Kaulfussia. 

 (b). Each loculus of the synangium opening by a termi- 

 nal pore; leaves simple or simply pinnate. 



DAN^ACE/E. Danaea. 



2. Plants leptosporangiate, sporangia developed from superficial cells. 



Leptosporangiat^. FILICALES. 



(1). Sporangia without a true annulus, but with a group of thick 



walled cells which are sometimes arranged in a ring at the 



apex or side; sporangia nearly sessile; sporophores usually 



different from the foliage leaves or leaflets. 



a. Sporangia with an irrigular group of dorsal thick-walled 

 cells, not arranged in a definite ring, globular; spores 

 with abundant chlorophyll. 



OSMUNDACE^. 



b. Sporangia with an apical ring of cells, ovoid. 



SCHIZiEACE^. 



(2). Sporangia provided with a true, complete or incomplete 

 annulus. 



a. Annulus usually complete; that is not interrupted by the 

 stalk of the sporangium. 



(a). Sporangia mostly 2 to 8, not on a prolonged or pro- 

 jecting receptacle; dehiscence vertical; indusium 

 none, veins free. 



GLEICHENIACE.E. 



(b). Sporangia on a convex, projecting or thread-like 

 receptacle; dehescence vertical, diagonal, or trans- 

 verse; indusium usually present. 



a. Sori round, on the end or the back, or in the 



axils of the veins. 



(a). Sori with 6 to 10 sporangia. 



MATONIACE.E. Matonia. 

 (b). Sori witli numerous sporangia. 



CYATHEACE^. 



b. Sori always on the leaf margin at the end of a 



vein; leaf texture filmy. hymenophyll.a.ce.e. 



b. Annulus incomplete, interrupted by the stalk of the 

 sporangium; dehiscence transverse; stalk usually long. 



a. Usually perennial terrestrial plants. 



POLYPODI.\CE^. 



b. Annual hydrophytes; sporangia sessile, scat- 



tered, covered by the reflexed margin of the 

 leaf. CERATOPTERiDACE/E. Ceratopteris. 



II. Sporophyte heterosporous, producing two kinds of nonsexual spores; 

 gametophytes much reduced, unisexual. 



1. Plants leptosporangiate, the sporangia in sporocarps, produced 



on the leaves; leaves without ligules. hydropterid^. 



a. Plants rooted, mostly perennial; sporocarp a modified 

 leaflet with a thick, hard wall; terminal bud with a 3 

 sided apical cell; megasporangia and microsporangia in 

 the same sorus. MARSILEALES. maksile.vce.e. 



b. Plants floating, mostly annuals; sporocarp thin walled, 

 representing a sorus; terminal bud with a two-sided 

 apical cell; megasporangia and microsporangia in sepa- 

 rate sporocarps. SALVINIALES. s.vlvixiace.-e. 



2. Plants eusporangiate; sporangia in the bases of the grass-like leaves 



not in sporocarps; leaves with ligules. 



Isoete^. ISOETALES. isoftace.e. Isoetes. Quillwort. 



