28 HEEEDITY AND EVOLUTION IN PLANTS 







ioglossum vulgatum, Fig. 28). The species of Bolry- 

 chium usually (though not invariably) possess but one 



FIG. 27. Rattlesnake fern (Botrychium virginianum (L.) Sw.). 



foliage-leaf, and a fertile spike, both of which are more or 

 less branched. Abnormal forms are not uncommon in 

 which the fertile spike is more or less sterilized, sometimes 



