214 



HEREDITY AND EVOLUTION IN PLANTS 



the genus-name, Bennettites. 1 Other forms, usually found 

 as casts, are called Williamsonia, still others are known 

 mainly as genera founded on leaf imprints. 



144. Cycadeoidea. In most of its purely vegetative 

 characters, such as the anatomy of the stem and the 



FIG. 98. Cycadeoidea Wielandi. Longitudinal section through the 

 axis of a female inflorescence, or cone. /, old leaf-base; d, insertion of 

 disc; s, erect seed, borne at summit of seed-pedicle inserted on convex 

 receptacle; b, hair-covered bract. (After Wieland.) 



\ 



structure of the leaves, Cycadeoidea resembled modern 

 cycads, but its reproductive branches were character- 

 istically lateral, which is one of the most fundamental 

 characteristics of the higher seed-bearing plants of to- 

 day. Only two modern^cycads (Macrozamia and Bow- 



1 Cycadeoidea Buckland = Benneltiles Carruthers. 



