﻿220 Maxon: Polypodium 



which suggests that reduction in the leaf expanse has taken place 

 inward to the boundary of the longitudinal series of simple areoles 

 constituting the venation of the leaf. The venation of P. grami- 

 neum is not precisely matched in any other species of Eupoly- 

 podium, but its peculiar character is certainly not of sufficient 

 weight to warrant giving more than minor rank, in classification, 

 to this species which is the type of Swartz's genus Grammitis. 

 In any event the actual structure is fundamentally different from 

 that of P. marginellum and its immediate allies, as may be noted 

 readily upon an examination of specimens, and clearly places 

 P. gramineum outside of this group. 



Polypodium marginellum Swartz, 1788, was the first species of 

 its own group to be described. It has since been very generally 

 misunderstood and has been regarded mistakenly in so broad a 

 sense as to include most of its allies, at one time or another, largely 

 because of insufficient material for study. Without tracing in 

 detail the varying treatment of the several forms, which is of 

 historical interest merely, it seems worth while to offer the follow- 

 ing key and brief synopsis, by means of which it is believed the 

 several species may be distinguished. 



Key to the Species 

 Fertile and sterile veins both mostly once forked, the branches 

 produced. 



greatly elongate stipe, deciduously ciliate with lax, deli- 

 cate, gland-tipped, mostly simple hairs, a few similar 

 hairs evident at first along the mid vein beneath; rhi- 

 zome scales evenly sinuate-dentate 



Sterile veins simple; fertile veins nearly simple, the elliptical 



gent as a short, oblique, translucent distal spur. 

 Rhizome scales rather lax, ligulate. yellowish brown in 



Rhizome scales rigid, subulate to acicular, reddish brown 

 in mass; sori distinctly inframedial, usually thrust 



Y sclerotic marginal band. . 



