18 POLYPODIACEAE 



mocks, and on palmettos in the Everglades. Figure 9, 

 reduced. 



The grass-fern or shoestring-fern, so called from the 

 very narrow elongate leaves, is widely distributed on 

 Royal Palm Hammock; but its growth is not as luxuriant 

 as if the cabbage-tree were more abundant, for it is 

 on the trunks of that palm that it seems to thrive 

 best. This fern is common in all the hammocks of 

 the neighboring Everglade Keys. Its distribution and 

 habitat correspond closely to those of the serpent-fern, 

 Phlebodium aureum. It is widely distributed in in- 

 sular and continental tropical America, and was dis- 

 covered in Florida in the latter part of the eighteenth 

 century. Besides occurring in southern Florida this 

 plant grows almost throughout the peninsula. 



6. PTERIS L. 



Coarse terrestrial plants, sometimes vine-like. Leaves 

 borne singly along the elongate rootstocks, sometimes 

 greatly elongate and clambering or climbing, the petiole 

 continuous with the rootstock: blades broad, triangular 

 or pentagonal in outline, or elongate, decompound, the 

 ultimate segments entire, toothed, or lobed. Veins free. 

 Sori linear, continuous, marginal, borne on a slender 

 receptacle which connects the ends of the free veins. 

 Indusium double, the outer prominent, formed by the 

 reflexed margin of the leaf-blade, the inner obscure, 

 borne upon the vein-like receptacle and extending be- 

 neath the sporangia. Several species of very wide geo- 

 graphical distribution. 



