120 OUR NATIVE FERNS AND THEIR ALLIES. 



fiat from an early stage, concealed under 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 R. Br. Fronds broadly lanceolate, smooth- 

 ish above, pinnate ; pinnae crowded, sessile, pinnately-parted, 

 the crowded segments oblong, obscurely crenate ; sori near the 

 margin, somewhat confluent when old. {W. rujidula Beck., 

 Acrostichum Ih'ense L., PoJypodium Ilvense Swz., Nephrodium 

 rufidulum Michx., Aspidium rufidulum Willd.) Virginia to 

 Kentucky, westward and northward. 



ft Fronds glabrous or nearly so. 



2. W. hyperborea R. Br. Stipes and rachis sometimes 

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

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

 Vermont, New York, and northwestward. 



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 sporangia. 



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

 ing, very chaft'y ; 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 



