COLLECTING THE MATERIAL 



In geological times the ancestors of the cycads were 

 numerous and widely distributed, but now there remains 

 only a single family with nine genera and about a hun- 

 dred species, all confined to tropical and subtropical 

 regions. The geographical distribution is very peculiar. 

 Of the nine genera, four belong exclusively to the Western 

 Hemisphere and five to the Eastern; all the western 

 genera, except one, are north of the equator, and this 

 one ranges from Florida to Chile; all the eastern genera, 

 except one, are south of the equator, the exceptional 

 genus ranging from Japan to Australia. 



Even in the warm regions, to which the cycads are 

 confined, their distribution is very restricted. Of the 

 western genera, one has been seen only in the province 

 of Pinar del Rio in Cuba; two are not known, with 

 certainty, outside of Mexico; the fourth, as we have 

 remarked, extends from Florida to Chile. Two of the 

 eastern genera are confined to Australia, two belong to 

 South Africa, while the other reaches from Japan to 

 Australia. Even in these places the plants occur singly 

 or in small patches, so that collecting is slow and more 

 or less uncertain. 



Without regard to possible interrelationships we 

 shall consider first the cycads of the Western Hemisphere 

 and then those of the Eastern. 



