CYCADALES 



113 



these sporophylls are farthest from the water supply. A large 

 cone may shed its pollen from the upper sporophylls several 



Fig. 107. — Zamia portoricensis: male cones of various ages on one plant. The micro- 

 sporophylls, although in strictly spiral arrangement, look as if they were in vertical 

 rows. The University of Chicago greenhouse (January, 1933). 



days before the lower ones dehisce (fig. 108). Like the cones, the 

 microsporophylls vary greatly in size; in Cycas circinalis, from 3 to 5 

 cm. in length and from 12 to 23 mm. in width; in Dioon edule, from 



