Nov., 1913.] 
The Classification of Plants, X. 
201 
Synopses of the Families of Filicales 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. 
OSMUND ACE^E. 
1. Fertile leaflets not at all or only slightly contracted. 
a. Epidermis with stomata. Todea. 
b. Epidermis without stomata; leaf blade thin. 
2. Fertile leaflets much contracted. Osmunda. 
Leptopteris. 
SCHIZ.-EACE.-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/E. 
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. 
II. 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.E. 
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; gametophyte flat or ribbon-like. 
Hymenophyllum. 
2. Receptacle projecting far beyond the indusium; sori marginal; 
indusium urn-shaped. Loxsoma. 
