24 DROUGHT KESISTANCE OF OLIVE IN SOUTHWESTERN STATES. 



labor. It can not be learned that during that time any fruit was 

 produced. A resident of Palm Springs who came there in 1896 

 recalls that they were "expecting the trees to come into bearing 

 the next year." About this time difficulties with the water supply 

 began, and as nearly as can be ascertained no irrigation at all has 

 been given the orchard since 1900. 



PRESENT CONDITION OP THE GROVE. 



The first fact with which one is impressed on seeing this plantation 

 is the small size of the trees considering their age. Some trees are 

 scarcely 4 feet high, and very few more than 7 or 8 feet. Taking 

 two average rows, the range in height was found to be from 41 inches 

 to 98 inches, the average for 50 trees being 63.5 inches. The high- 

 est tree in the 20-acre block was found to be 9 feet, while only 10 

 trees could be found measuring 8 feet and upward. (See PI. Ill, 



fig. 2.) 



It is to be noticed that on these trees the branches are retained 



clear to the ground and that the breadth of the top exceeds the 



height in almost every case, so that in the 50 trees examined only one 



was found in which the height was greater than the breadth of top. 



The average breadth for the two rows is 79.5 inches as against 63.5 



inches of height. These tops, too, are much branched and very 



compact. In nearly every case the trunk is concealed. A leafy 



canopy protects the trunk and main branches from the dry air and 



fierce heat of the desert sun. 



In doing battle for their lives in the desert they have sliowTi their 

 ability to adapt themselves to desert methods of defense. The mes- 

 quite and paloverde,"^ the largest native trees, may attain a spread 

 of top of 40 or 60 feet with a height of only 20 or 30 feet. The 

 desert willow (Chilopsis) and the Dalea spinosa, two species somewhat 

 less resistant to drought and heat, attain a treelike size by throwing 

 out a defense of sprouts and low branches, or, failing in this, they are 

 apt to show scars of severe sun scalding. 



The so-called "wild apricot" (Prunus fremontii) , venturmg out a 

 little way along the bowlder talus from the canyon's mouth, has a 

 top so densely branched, angled, and interlocked as to well merit the 

 name Emplectocladus, signifying interlocked branches, which now 

 applies to the whole subgenus to which it belongs. 



Similar proportions of height to spread of top will be found in 

 nearly all of the characteristic desert shrubs, the effort seeming to be 

 to throw as much shade and insulation as possible around the trunk 

 and main branches. 



o-Cercidium torreyanum (Wats.) Sargent. 

 192 



