22 DESERT BOTANICAL LABORATORY 



species of the same genus, and the composite green leaved Peucephyl- 

 lutn schottii. 



West of Indio the railroad passes through a strip of mesquite dunes. 

 Most of the sand here lies in hummocks, each the product of a mes- 

 quite tree {Prosopis) about which, and finally through the branches 

 of which, the sand has drifted until only the ends of the branches 

 project and the hummock presents the appearance of being covered 

 with a growth of brambles. 



Between Rimlon and Palm Springs is an area in which the vegeta- 

 tion is subjected to strong sand laden winds, a veritable sand blast. 

 The western faces of the wooden telegraph poles ai^e deeply cut within 

 two feet of the ground by the sharp, driving sand, and the railroad 

 employees have found it necessary to pile stones about the bases of the 

 poles in some spots to keep them from being actually cut off. The 

 creosote bushes have been moulded into the most fantastic shapes. One 

 of them standing in the lee of a small boulder ran its branches freely to 

 the eastward, but the twigs that projected upward and outward beyond 

 the protection of the boulder were killed by the sand blast, so that the 

 plant presented the appearance of a miniature box hedge about a foot 

 and a half high and wide, and extending about four feet from the rock. 



Clumps of Ephedra and plants of Tucca mohavenszs, the cylin- 

 drical stemmed Opuntia bigelovii and O. echinocarpa^ and the flat 

 stemmed spineless O. basilaris vary the desert vegetation until, in the 

 vicinity of the station Cabezon, the creosote bush ceases and the white 

 sage {Ramona polystachya) and various other plants from the coast- 

 ward side of the San Bernardino-San Jacinto mountain barrier come 

 out a little way through San Gorgonio pass to meet the plants of the 

 desert. 



THE MOHAVE DESERT. 



Ascending from the San Bernardino valley northward through the 

 long climb of Cajon pass, the railroad at last emerges from the dense 

 growth of chaparral and comes out upon the elevated plain of the 

 Mohave desert. About four miles north of the summit begin to occur 

 small groves of the strange tree for which the western part of the 

 Mohave desert is most widely known, the tree yucca ( Tucca arbores- 

 cens). Within a few miles the desert becomes almost a forest of yucca 

 and juniper {Juniperus calif ornica')^ the former reaching a height, 

 ordinarily, of 12 to 15 feet, though occasionally exceeding 25 feet and 

 attaining a diameter of nearly two feet. At the station Hesperia the 

 juniper ends and the creosote bush ( Covillea tridentata) begins. As 

 still lower elevations are reached, the creosote bush becomes, except 



