POLYPODIACEAE 9 



It seems to have been first collected in Florida in the 

 early part of the last century on Key West and on Big 

 Pine Key. Insular and continental tropical America 

 are also inhabited by this fern. 



FAMILY 4. POLYPODIACEAE 

 FERN FAMILY 



Terrestrial, epiphytic, or aquatic plants. Root- 

 stocks elongate, creeping or horizontal, or short and 

 erect. Leaves sometimes dimorphous, coiled in ver- 

 nation, erect, spreading, or pendulous: blades simple, 

 once-pinnatifid or several times pinnatifid or pinnate, 

 or decompound. Sporangia borne either promis- 

 cuously or in clusters (sori) on the lower side or 

 margins of the leaf -blades, stalked, provided with an 

 incomplete vertical ring of thickened cells, opening 

 transversely. Sori either with or without a mem- 

 branous covering (indusium)., Prothallia green. 

 The largest of "the families of ferns. It includes 

 nearly one hundred and fifty genera and nearly five 

 thousand species. It is represented in arctic, tem- 

 perate, and tropical regions. 



Spore-bearing leaflets densely clothed with masses of sporan- 

 gia. I. ACROSTICIIEAE. 



Spore-bearing leaflets, or leaf-seg- 

 ments, with sporangia borne In 

 separated sori. 

 Indusia wanting. 



Sori broad, circular or nearly 



so, or elliptic, not marginal. II. POLYPODIEAE. 

 Sori linear, in continuous or in- 

 terrupted marginal or intra- 

 marginal lines. III. VITTAEIEAE. 



Indusia present. 



Sori marginal or essentially 

 so : indusium formed in 

 part of the more or less 

 modified leaf-margin. 

 Sporangia borne on a con- 

 tinuous vein-like recep- 

 tacle connecting the 

 apices of the veins. IV. TTKRIDEAE. 



