PTERIDOPHYTA Cohn. 



Vascular acrogens containing woody tissue in the stems. 

 Antheridiaor archegonia or both formed on a prothallus which 

 is developed from the spore on germination, and upon which 

 the asexual plant is produced. Includes eight living and three 

 extinct orders, all represented in North America. 



ARTIFICIAL SYNOPSIS OF ORDERS. 



* j Isosporous, i.e., spores of one kind B 



( Heterosporous, i.e., spores of two kinds D 



f Plant rush-like, . . . Order V. EQUISETACE^E, p. 132 



B j Plant moss-like, . . Order VI. LYCOPODlACEjE, p. 135 

 [Plant fern-like C 



I Vernation erect or inclined ; sporangia not reticulate, 

 in spikes or panicles, opening by a transverse slit. 



Order IV. OPHIOGLOSSACE^E, p. 128 

 C \ Vernation circinate ; sporangia reticulate, provided 

 with a ring, usually borne on the back or margin of 

 a frond sometimes in spikes or panicles, 



Order I. FlLICES, p. 75 



f Terrestrial, moss-like plants, 



j Order VII. SELAGINELLACE^E, p. 140 



j Aquatic, rooting in mud, E 



[ Aquatic, floating, . .Order III. SALVINIACE^E, p. 127 

 j Leaves awl-shaped, tubular, containing the sporangia 



in their axils, . . . Order VIII. ISOETACE^E, p. 142 

 E -j Leaves quadrifoliate or filiform ; sporangia enclosed 



in sporocarps borne on separate peduncles, . . . 

 [ Order II. MARSILIACE^E, p. 125 



ORDER I. FlLICES Juss. 



Plant body consisting of fronds usually raised on stipes ris- 

 ing from a prostrate, ascending, or erect rootstock, circinate in 

 vernation. Sporangia modified trichomes of the leaves, reticu- 



