1 8 DESERT BOTANICAL LABORATORY 



fruit which during the season of drouth is an important source of 

 refreshment to wild animals and even to man. The other common 

 cylindrical stemmed Opuntia^ called cholla, has several times thicker 

 joints and grows only 2 or 3 feet high but forms large patches which 

 are a conspicuous feature of the vegetation. Other woody plants 

 showing adaptations to desert conditions are sangre de drago * {Jatro- 

 pka) a shrub with whip like, at this season wholly leafless brown 

 stems, from which the Papago Indians make some of their baskets ; 

 vinorama, a tree acacia (^A. farnesiana) with yellow scented flowers; 

 papachi, a small rubiaceous tree {Rand/a thurberi) with fruit resem- 

 bling in appearance a small green orange ; bebelama, an unidentiHed 

 tree with a trunk sometimes 18 inches in diameter, its wood so hard 

 and tough that it is commonly used for wagon fellies ; and desota, a 

 tree mimosa with pink flowers having the delicious odor of the black 

 locust flower {Robtnia pseudacacid). This desert produces also 

 several malpighiaceous and other woody vines which associate them- 

 selves with clumps of the trees and shrubs. Among these vines are 

 the saramatraka, a tuberous rooted cereus with branching stems 0.2 

 to 0.3 inch in diameter, which reach a length of 4 feet or more, 

 growing through and reclining upon the bushes ; and the guarequi 

 {Ibervillea sonorae)^ a cucurbitaceous tendril bearing plant whose 

 inordinately thickened root and stem base sits white and half exposed 

 upon the ground beneath some trellising shrub (Plate XVI). 



Westward from Torres the vegetation of the desert continues with lit- 

 tle change until the line of hills is approached beyond which the coun- 

 try drops down to a plain still lower and nearer the waters of the Gulf. 

 Here are the tree ocotillo {^Fouquieria ?nacdougalii) (Plate XVII), 

 brasil {Haematoxylon) ^ torote prieto {Bursera)^ the tree morning 

 glory {Ipomoea arborescens)^ and the beautiful palo lisso {Acacia 

 willardiana) . This last is a small tree with the whitest of bark 

 peeling off in tissue paper films, a slender trunk with graceful spread- 

 ing branches, and curious compound leaves made up mostly of flat 

 green rachis with an extremely small leaflet area toward the summit. 

 The morning glory is a tree 20 to 30 feet high, with smooth chalky 

 gray trunk and branches, leafless at this season throughout, its large 

 white flowers opening one by one on the ends of the naked branches. 

 From its white bark the tree is sometimes known as palo bianco, and 

 from the gum or resin which exudes from incisions made in it for the 

 purpose and which is used as incense in religious ceremonies it is 

 called also palo santo. Two trees pass under the name torote bianco, 



* Locally corrupted to sangrengrado. 



