So 



THE LIVING CYCADS 



sun of Northern Australia still looked fresh after three 

 days. 



Crowns, as we have already noted in considering the 

 age of. plants, are produced at rather regular intervals 

 in the field, but in the greenhouse the leaves last much 



Fig. 26. — Dioon spinulosum: radial longitudinal section of mature 

 wood, showing the numerous pits; a thin-walled cell (/) in the wood is 

 also shown. 



longer. Dioon spinulosum, in the field, may produce a 

 crown every year, and Dioon edule every other year; 

 but in the greenhouse the interval may be four or five 

 years. 



In the field Dioon edule generally has one bright, 

 fresh crown and a gray-green crown, the lighter color 



