XXII1 



MORPHOLOGY 



155 



except JMohria they are simple and filamentous, as they are in the Botryo- 

 pterideae and Osmundaceae, and many other primitive Ferns. 



The sporangia are not grouped in sori, but they are solitary, a number of 

 them being borne on each fertile segment. In Sc/iirjaea and Aneuiia they 



A B 



Pig. 438. Lygodiiiiii pal/natnni Sw. Leaves, showing their venation. .-7, sterile: j5, fertile. (After 

 Prantl, from Engler and Prantl.) 



Fig. 439. Alohi-ia caffroruiii (L.) Desv. A, part of a sterile leaf: B, a fertile pinna. (After Diels, 

 from Engler and Prantl. ) 



appear disposed when mature in regular rows, one on each side of the 

 midrib, on the lower surface of the fertile segments. In Lygodimn and 

 Mohria one is seated near each vein-ending (Fig. 441). They may be pro- 

 tected by the curled margin of the pinnule, as in Mohria and Schisaea: or 



