Brittle Fern. 
Plants sometimes 4 dm. high, but usually smaller, 
delicate ; leaves lanceolate, 3-pinnatifid ; pinnae ovate- 
lanceolate, 4 cm. or less 1. ; pinnules ovate, decurrent 
on the rachilla, lobes entire or toothed. 
In rocky places. Summer. 
20. WOODSIA R. Br. 
This geniis I have 7iained in honor of my friend 
Mr. Joseph Woods , , R. Brown, 18 15. Trans. Linn. 
Soc. 11:171. 
Rootstock short, ascending. Leaves 2-pinnatifid to 
2-pinnate. Sori situated near the end of the veinlets. In- 
dusium globular, at length splitting into numerous lobe^-. 
t Leaves 2'pin?iatifid., pinnae somewhat crowded, 
1. W. ilvensis (L.) R. Br. 
Acrostichum ilvense L. Sp. PI. 1071. 
Woodsia ilve?tsis R, Br, 1. c. 173. Eaton ^ Ferns 
N. A. 2 : 1 1 1 . t. 60. ff. 5-8 ; in Gray, Man. 690. 
Underw, in 111. Fl. i : 10 ; Nat. Ferns 121 ; in 
Britt. Man. 18. C/^//^?, Ferns 93. Waters^Ferns> 
273. 
Rusi'Y Woodsia. 
50 
