Onoclea, Woodsia. 95 



I 2. STRUTHIOPTERIS, Willd. Veins all free. 



2. O. Struthiopteris, Hoffm. (Ostrich-fern.) Fertile fronds 

 1° — \yz° long, simply pinnate with necklace-shaped pinnee formed 

 of the strongly revolute margins ; sterile frond, as — 6s long, grow- 

 ing In a crown, broadly lanceolate, bipinnatifid, the lowest pinnfe 

 gradually much shorter ; veins pinnate, free, and simple ; sori 

 crowded and confluent. Sterile fronds sometimes partially con- 

 tracted and bearing sori analogous to var. obtusilobata above. 

 [Struthiopteris Germanica, Willd.) N. Eng. to 111. II. 



XXin. WOODSIA, R. Br. 



Sori round, borne on the back of simply-forked free veins. 

 Indusium inferior, thin and often evanescent, either small and 

 open, or early bursting at the top into irregular pieces or lobes. 



\ I. EUWOODSIA. Indusium minute or evanescent, open 

 and flat 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. 



^Fronds thickly clothed underneath with rusty bristle-like chaff. 



1. W. Ilvensis, R. Br. Fronds broadly lanceolate, smoothish 

 above, pinnate ; pmnas crowded, sessile, pinnately-parted, the 

 crowded segments oblong, obscurely crenate ; sori near the mar- 

 gin somewhat confluent when old. Va. to Ky. westward and 

 northward. II. 



\^ Fronds glabrous or nearly so. 



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

 hairy; fronds linear-lanceolate, pinnate; pinnae cordato-ovate, 

 pinnatifid with few (5 — 7) broadly obovate entire lobes. Vt., N. Y., 

 and northwestward. II. 



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 sub- 

 cuneate entire lobes. Vt., N. Y. and northward. II. 



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

 by the sporangia. 



4. W. scopulina,* D. C. Eaton. Rhizoma short, creeping very 

 chaffy ; stipes 1' — 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; piimse numerous, oblong- 

 ovate, pinnatifid with 10—16 short ovate or oblong toothed divi- 



