20 EUCALYPTUS, 



in the resistance of the trees they produce to unfavorable 

 climatic conditions, and these variations correspond with 

 the climatic conditions where the seed produced grew. 



It seems only resonable to presume that this quality 

 would extend also to the seeds of the blue gum. Our 

 California plantations of blue gum are now practically all 

 made from locally gathered seeds. 



Doubtless, too, the prevalence of conditions, such as 

 prolonged drought, whereby the tree remains dormant 

 during the periods of exposure, would prove favorable to 

 resistance of frost. The vegetable world, in this respect, 

 is the opposite of the animal. There are indeed hiber- 

 nating animals that remain dormant during the winter, 

 living on themselves, but no animal can resist extreme 

 cold so well with diminished as with active circulation. 

 In the vegetable world the opposite condition prevails. 



Animals suffer most from cold when exposed to wind. 

 With plants it is exactly the reverse. At least such is the 

 fact in the semi-tropics. A breeze on a cold night is con- 

 sidered a protection against frost. It is a wise precaution 

 to discourage active sap circulation in delicate plants as 

 periods of possible frosts approach. In irrigated sections 

 this may be done by withholding water in the fall. 



As the young Eucalyptus is more susceptible than the 

 old to frost so we find numerous sections where this tree 

 does well if the young are protected with straw, gunny- 

 sacks or any light covering; indeed just as young orange 

 and lemon trees are in some of our interior plateaus. In 

 these sections the citrus fruits are a success, but every now 

 and again a great deal of snow falls in the neighboring 

 mountains and the* night air descending to the valleys is 

 colder than usual. When to this condition we have added 



