80 Ebony Spleen wort 



manes. The color that replaces the green appears first at the 

 petiole's base and spreads upward, involves in time the entire 

 rachis, and, occasionally, in the larger leaves, encroaches also on 

 the under surface of the pinnae, along the midveins. It is straw- 

 color at first, but gradually becomes chestnut-brown or darker, 

 finally shading from brown to ebony and, occasionally, tinged 

 with green. 



Auricles at the bases of the pinnae are absent in the first early 

 stages of the leaf's development, but a tendency toward especial 

 development at the places where they are to appear later is early 

 noticeable. For instance, in many of the pinnae of very young 

 leaves the midvein's superior basal primary branch, which later 

 forms the midvein of the superior auricle, is once forked, while the 

 other primary branches are simple. The auricles gradually 

 form as the leaf develops, sometimes at the inferior sides of the 

 pinnae as well as at the superior. They are in reality incipient 

 secondary segments of the leaf. 



Although the leaf-blade's margin is sometimes subentire or 

 merely undulate, a greater or less degree of incision between the 

 primary branches of the leaf's midveins, or at least a tendency to 

 such incision, is noticeable in all stages of the leaf. It is obvi- 

 ously carried to its fullest extent in the production of the pinnae. 

 In the pinnae themselves it is commonly shown merely by serra- 

 tion or crenation or undulation of the margin, but sometimes it 

 is carried far enough to render the pinnae cleft, more or less 

 deeply, into segments. 



The so-called " var. serratum" Gray is based upon leaves 

 with such cleft pinnae. These leaves are not uncommon in 

 large, luxuriant, fertile plants, and represent, apparently, the 

 height of normal development of this fern's leaf. They are 



