168 THE ROCK SPLEENWORTS. 



The rootstock is short, nearly erect and usually roots 

 in a crevice well out of ordinary reach. The fronds, some 

 six inches or less in length, are broadest at base and taper 

 outward to a long slender tip that often roots after the 

 manner of the walking fern ; in fact the whole plant sug- 

 gests the latter species and it is not surprising to learn 

 that it was once considered a variety of it. It is, however, 

 clearly distinguished by its free veins, and mostly single 

 indusia, not to mention its pinnatifid fronds. 



The fronds are thick and evergreen. At some dis- 

 tance from the tip they begin to be round lobed and these 

 lobes grow larger and the cutting deeper as the base is 

 approached, until the lowest often become separate pinnae, 

 rather rounded triangular in outline. The stipes are 

 usually short, but vary in. length with the location of each 

 plant, being always long enough to lift the blade clear of 

 the crevice in which it is rooted. There is consid- 

 erable variation in the fronds. Forms that are pinnate 

 nearly to the summit, with ovate pinnae, have been found, 

 and others with long, sharp-pointed pinnae at the base of 

 the frond are known. The sori are borne both upon the 

 lobes and the tapering apex, many of them opening 

 toward the inferior edges. 



The pinnatifid spleenwort is found from New York to 

 Illinois, Arkansas and Georgia. Throughout most of its 

 range it is extremely rare though in some small sections it 

 is not uncommon. It has been found on limestone, gneiss 

 and sandstone and will probably yet be found on shale. 

 Within its range the collector is always warranted in 

 expecting it, though he is probably destined to be very 

 frequently disappointed. 



