CYCADALES 



153 



len of Z. floridana. The sporophylls of the female cones were tightly 

 closed, and it is more than doubtful whether any of the pollen sur- 

 vived the usual spraying. A week later sporophylls of both female 

 cones opened and Dr. Paul J. Sedgwick pollinated them with 

 Zamia piimila. One cone produced three seeds, and the other, four. 

 All were planted, and four of the seven have developed into vigorous 

 Fi plants, two of them female and two male. The first of these four 



Fig. 170. — Ceratozamia mexicana X Zamia monticola, Fi seedlings: 5, seed; c, cotyle- 

 dons; b, bud; r, primary root; ar, apogeotropic root; co, coleorhiza; a, egg membrane: 

 A, B, and C, with two cotyledons: D, with only one; C, embryo in female gametophyte; 

 C", transverse section of embryo with two cotyledons. — After Chamberlain."^ 



to cone produced a small male cone which shed its pollen in January, 

 1928. So, the male cone appeared while the plant was only 6 years 

 old. 



In 1929 three of the /^i plants produced cones, one female and two 

 males. One of the males shed all of its pollen before the sporophylls 

 of the female opened; but the second male cone was still shedding 

 pollen at the right time, and from this pollination good seeds were 

 secured and several F2 plants are thriving. 



Ceratozamia mexicana X Zamia monticola. ^^^ — -A generic cross be- 

 tween Ceratozamia mexicana and Zamia monticola was particularly 

 successful. One cone was pollinated March 23, 1924, and another, 

 on a different plant, on April 25, 1924. From these two cones more 



