Ebony Spleenwort 8i 



somewhat analogous to the highly developed leaves in Polystichum 

 acrostichoides. 



The cleft pinnae are mostly unusually long, and commonly 

 occur in the more central part of the leaf-blade, which is, as a 

 rule, the most highly developed part of any mature leaf of this 

 fern. The primary branches of the pinnae's midveins are mostly 

 more complex in the cleft pinnae than in the others, excepting 

 those in the basal auricles of the latter, and constitute the seg- 

 ment's midveins. Series of sori occur along these midveins as 

 well as along the pinnae's midveins. In the uncleft pinnae series 

 of sori occur only along the pinnae's midveins and the auricles' 

 midveins. The auricles, which, as already stated, are incipient 

 segments, become basal segments in the cleft pinnae. 



In this fern, as in ^. angustifolium* diplazioid sori, or dipla- 

 zioid parts of sori, sometimes occur on veins that are both primary 

 branches of one midvein and superior basal primary branches of 

 primary branches of another. 



In addition to the incision described above, employed in the 

 leaf's development, slight incision, or a tendency to slight incision, 

 between the leaf's ultimate veinlets is often noticeable in the leaf 

 at various stages. When present it adds to the unevenness of the 

 leaf-blade's margin, and in highly developed leaves causes the 

 pinnae's segments to appear toothed. 



"Var. Hortonas" Davenport is based upon monstrous leaves 

 in which incision occurs in an extreme degree and is correlated, 

 so far as known, with total sterility of the leaf. 



* See page 60. 



