214 



HEREDITY AND EVOLUTION IN PLANTS 



the genus-name, Bennettites} Other fbrms, 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; J, erect seed, borne at summit of seed-pedicle inserted on convex 

 receptacle; J, 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- 



'■ Cycadeoidea Bucklan'd = Bennetiites Carruthers. 



