WOODSIA OBTUSA. 

 COMMON WOODSIA. 



NATURAL ORDER. FILICES. 



WooDSiA OFTUSA, Torrey. — Frond sub-pinnate, or nearly tri-pinnate. Minutely glandular- 

 pilous; leaflets distant; segments of the leaflets pinnatifid; ultimate segments roundish- 

 oblong, obtuse, bi-dentate ; sori round, one at each cleft between the leaflets, at length 

 crowded ; stipe somewhat chaffy. Fronds lance-oblong in outline, three times as long 

 as wide. Segments of the leaflets crevate-serrate, the lower ones distinct, upper con- 

 fluent. Sori orbicular, becoming nearly confluent, each at first enclosed in the silvery 

 indusium which when open is notched into little teeth on the margin. (Wood's Class- 

 Book of Botany. See also Gray's Flora of the Northern United States, Chapman's 

 Flora of the Southern United States, and Williamson's Ferns of Kentucky.) 



ilLONG the Wissahickon Creek, in Falrmount Park, Phila- 

 delphia, and from whence the plant was taken which 

 served us for an illustration, this fern is not uncommon, and 

 it is remarkable that it is almost always to be found on dry walls 

 — that is to say, walls built of stone without mortar — when these 

 walls are in a damp or shady place. The little ledges formed by 

 the stones, and the little spaces between the stones in the wall, 

 are favorite situations with this fern, as also are those parts of 

 the stone breastworks of dams over which the water does not 

 actually flow. Occasionally it is found in the crevices of rocks, 

 but the collector will be much more likely to meet with it in this 

 Park by going to the nearest old wall than to any other place. 



It is a very interesting fern, though in all that constitutes 

 beauty, there are others superior to it. One of its happiest 

 phases is towards the fall of the year, when the short barren 

 fronds which form the outer circle bend downwards, forming a 

 sort of rosette, in the centre of which the fertile fronds some- 

 what erectly stand. In the part of our country where our illus- 

 ' 4 (49) 



