Nov., 1913.] The Classification of Plants, X. 201 



Synopses of the Families of Filic\les Containing More Than 



One Genus. 



No complete presentation is given of the Polypodiaceae, but a few genera 

 are named under each subfamily to indicate the general trend of the phyletic 

 series. 



OSMUNDACE.E. 



1. Fertile leaflets not at all or only slightly contracted. 



a. Epidermis with stomata. Todea. 



b. Epidermis without stomata; leafblade thin. 



Leptopteris. 



2. Fertile leaflets much contracted. Osmunda. 



SCHIZiEACE.E. 



1. Vascular strand central. 



a. Leaves erect, spores bilateral. Schizaea. 



b. Leaves twining, spores not bilateral. Lygodium. 



2. Vascular bundles forming a net-like hollow cylinder in the stem. 



a. Sporangia single or rarely in twos at the end of the 

 vein. Mohria. 



b. Sporangia in two rows along the midrib of the leaf 

 segment. Ornithopteris. 



GLEICHENIACE^. 



1. Rhizome erect; leaves simply pinnatified. Stromatopteris. 



2. Rhizome creeping; leaves mostly dichotomously branched. 



Gleichenia. 



CYATHEACE/E. 



I. Sori at the ends of the fertile veins; indusium forming a cup-like sheath 

 together with the more or less modified leaf tip around the sorus. 



1. Annulus of the sporangium with a stoma or mouth of specialized 



cells. 

 (1). Fertile lobe of the leaflet slightly or not at all modified; 

 forming with the indusium a two-valved cup. 



a. Stem not raised above the ground or only slightly so 



Balantium. 



b. Aerial stem erect, well developed. Dicksonia. 



(2). Fertile lobe of the leaflet highly modified, similar to the 

 Indusium. Cibotium. 



2. Annulus of the sporangium with cells all alike. Thyrsopteris. 



n. Sori on the back or in the fork of the fertile veins; indusium inferior; 

 annulus of the sporangium of nearly similar cells, the mouth only slightly 

 differentiated. 



1. Sorus without indusium. Alsophila. 



2. Sorus with an indusium. 



a. Indusium scale-like. Hemitelia. 



b. Indusium cup-like, with a smooth margin or at first 

 closed and later breaking irregularly. Cyathea. 



HYMENOPHYLLACE.^. 



1. Receptacle not projecting far if at all beyond the indusium. 



a. Indusium tubular or cup-shaped; gametophyte filamen- 

 tous. Trichomanes. 



b. Indusium two-lipped; gametophj^te flat or ribbon-like. 



Hymenophyllum. 



2. Receptacle projecting far beyond the indusium; sori marginal; 



indusium urn-shaped. Loxsoma. 



