3S8 



MOSSES AND FERNS 



CHAP. 



any distinct lamina. The fertile leaves are pinnately divided. 

 In other species, e. g., S. dichotoma, the leaves are dichoto- 

 mously divided, but the fertile leaf-segments are pinnate, as they 

 are in 5". pusilla ( Diels ( i ) ) . 



In Aneimia (Fig. 225) the two lower pinnae of the sporo- 

 phyll are fertile, and in most species become very long-stalked 

 and more divided than the sterile pinnae. The leaves arise from 

 the dorsal side of the rhizome and in Lygodium, Prantl (5) 

 states that they form but a single row. He also says that the 



Fig. 226. — A, Apex of a young, fertile leaf-segment of Aneimia PhylUtides, X200; 



B, transverse section of young fertile leaf-segment of Schisaea Pennula, Xioo; 



C, part of a similar section of a somewhat older leaf, Xioo; sp, young sporangia; 

 in, indusium. (All figures after Prantl.) 



roots are always diarch, like the Polypodiaceae, but gives no 

 further details of their growth or structure. 



The Sporangium 



The development of the sporangia has been carefully in- 

 vestigated by Prantl (5) and in origin and arrangement they 

 differ decidedly from the other Leptosporangiates, but approach 

 most nearly Osmunda, and among the eusporangiate Ferns 



