SEED-BEARING PLANTS 41I 



364. Distribution. — The cycads and their relatives are 

 all tropical or subtropical. Four genera (Microcycas, 

 Zaniia, Ceratozamia, Diobn) occur in the western hemi- 

 sphere, with the chief center of distribution in Mexico; 

 and five genera {Cycas, BouTuia, Macrozamia, Encephal- 

 artos, and Stangeria) in the eastern hemisphere, with 

 the chief center of distribution for the first three in Queens- 

 land, Australia. Encephalartos and Stangeria are confined 

 to Africa. 



