176 STRUCTURE AND LIFE HISTORIES 



Botrychiiim usually (though not invariably) possess but 

 one foHage-leaf, and a fertile spike, both of which are 



Fig. 133. — Rattlesnake fern {Botrychiiim virginlanmn {h.) S\v.), 



more or less branched. Abnormal forms are not un- 

 common in which the fertile spike is more or less steril- 



