"145 °"^ every single one of them is right 



That the coral bean's reliance on as simple a mecliani- 

 cal device as the waxy coating works well, seems to be 

 demonstrated by the fact that the plants are quite com- 

 mon in rocky canyons at moderate altitudes and their con- 

 spicuous scarlet flowers add a brilliant touch to the early 

 summer landscape at a time when most spring flowers are 

 past and those of late summer have not yet appeared. 

 Nevertheless, many other plants prefer to depend instead 

 upon the subtler operations of biochemistry. There is no 

 visible reason, only a chemical one, why the seeds refuse 

 to come up except at the one time a year when they can 

 establish themselves. 



In many parts of the world many plants solve their usu- 

 ally simpler problem in a similar way. Many a wild an- 

 nual drops its seeds by midsummer when the soil is both 

 warm and damp, but the seeds refuse to grow until the fol- 

 lowing spring when they v^dll have before them a season of 

 warmth long enough to permit them to come to maturity. 

 Sometimes their secret is that certain necessary chemical 

 preliminaries to growth are not complete when the seed 

 falls but take place while it is apparently dormant. Some- 

 times it is that a winter's cold is necessary before the 

 chemistry is right for growth. "Unless the seed die . . ." 

 And dying in these cases means being chilled as well as 

 dried out. 



In southern Arizona things are less simple. There is the 

 very long hot summer but there are only two very short 

 wet seasons. Some plants flourish just after the first one, 

 which ends about as spring begins; others, during and after 

 the brief midsummer rains. The seeds of both lie in the 

 ground all winter and those of the first sort during most of 

 at least one summer as well. But the seeds of spring flow- 



