POL YPODIA CE.-E. 1 2 t 



fiat from an earfy stage, concealed tinder the sorus, its margin 

 cleft into slender hairs or cilia. 



* Stipes obscurely jointed near the base ; cilia of the indusium 

 long, inflexed over the sporangia. 



t Fronds thickly clothed underneath 'with rusty bristle-like 

 chaff. 



1. W. Ilvensis (L.)- R- Br. Fronds broadly lanceolate, 

 smoothish above, pinnate; pinnae crowded, sessile, pinnately- 

 parted, the crowded segments oblong, obscurely crenate; sori 

 near the margin, somewhat confluent when old. ( W. rufidula 

 Beck., AcrosticJmm Ilvense L., Polypodium Ilvense Swz., Ne- 

 phr odium rufidulum Michx., Aspidium rtifidulum Willd.) Vir- 

 ginia to Kentucky, westward and northward. 



ft Fronds glabrous or nearly so. 



2. W. alpina (Bolt.) S. F. Gray. Stipes and rachis often 

 slightly hairy ; fronds linear-lanceolate, pinnate; pinnae corda- 

 to-ovate, pinnatifid with few (5 7) broadly obovate entire lobes. 

 Vermont, New York, and northwestward. ( W. hyperborea R. Br.) 



3. W. glabella R. Br. Smooth and naked throughout ; 

 fronds linear, tapering slightly below, 2' 5' high, pinnate ; 

 pinnae deltoid or ovate, the lower rather remote, cut into 3 7 

 rounded or subcuneate entire lobes. Vermont, New York, and 

 northward. 



** Stipes not jointed ; cilia of the indusium very short, hid- 

 den by the sporatigia. 



4. W. scopulina D. C. Eaton. Rootstock short, creep- 

 ing, very chaffy ; stipes 2' 4' long, puberulent like the rachis 

 and under surface of the frond with minute flattened hairs and 

 stalked glands ; fronds lanceolate, 4' 8' long, pinnate ; pinnae 

 numerous, oblong-ovate, pinnatifid with 10 16 short ovate or 

 oblong toothed divisions ; indusia very delicate, deeply cleft 

 into laciniae which terminate in short hairs. Colorado, Ari- 

 zona, California, Oregon, and northward. 



5. W. Oregana D. C. Eaton. Stipes and fronds smooth ; 

 fertile fronds taller than the sterile ones; pinnae triangular-ob- 

 long, pinnatifid ; segments oblong or ovate, toothed or crenate; 

 teeth often reflexed and covering the submarginal sori ; indusia 



