GVMXOSPERMS 



The largest cone described is that of Macrozamia dcnisonii, which 

 in extreme cases reaches a length of 80 cm. and a diameter 20 cm. 



In Enccphalartos aUcnsteinii 

 the longest reported was 60 

 cm., with a diameter of 12 cm. 

 Other measurements are, Cy- 

 cas circinalis, 45 cm.; Cycas 

 rcvoluta, 40, Dioon spinulosum, 

 40; Dioon ediile, 30; Dioon 

 pnrpusii, 20; Zamia Jioridana, 

 10; Bowenia serrulala, 5; and 

 Zamia pygmaea, 2 cm. 



These are the maximum 

 measurements. The average 

 cones are not much more than 

 half as long. Measurements of 

 the same cone, taken 48 hours 

 apart, might be very different; 

 for just before shedding the 

 pollen, the cone elongates im- 

 mensely and rapidly, so that 

 the sporangia are freely ex- 

 posed. 



The microsporophylls are 

 spirally arranged in acropetal 

 succession, but the arrange- 

 ment is so absolutely regular 

 that, in surface view, they 

 often look as if they were in 

 vertical rows, like the grains 

 of corn on a cob (fig. 107, and 

 see also fig. 106). 



While the arrangement is 

 spiral and acropetal, so that 

 the sporophylls at the top 

 are the last to be formed, they are the first to ripen their pollen, 

 probably because the ripening depends largely upon drying, and 



Fig. 106. — Dioon ediilc: male cone, photo- 

 graphed at Chavarrillo, a short distance east 

 of Jalapa, Mexico. September, 1906. One- 

 third natural size. /\ftcr Chamberlain."* 



