SPERM VTOPHYTES 



95 



Ovulate. — The 

 ovulate strobili (fig. 

 442) are sometimes 

 very large. The 

 genus Cycas is 

 peculiar in its ovu- 

 late strobilus, in 

 that it is not a com- 

 pact strobilus, but 

 a rosette of spo- 

 rophylls resembling 

 reduced foliage 

 leaves, in which 

 ovules replace the 

 lower pinnae or 

 teeth (figs. 443, 444). 

 In general, the spo- 

 rophylls vary from 

 the leaflike (pin- 

 nate) forms of Cycas 

 to peltate forms (as 

 in Zamia, fig. 441, 

 and Ceratozamia, 

 fig. 445). Between 

 these extreme forms 

 there is a complete 

 series of transitions, 

 but there is always 

 a terminal sterile region of varying form. The ovules vary in number 

 from five or six to two. 



Fig. 439- 



Staminate strobili of Dioon. — After 

 Chamberlain. 



Figs. 440, 441. — Stamens (microsporophylls) of Cycas circiiiulis (440) 

 integrifolia (441). — After Richard. 



id Zamia 



