96 THE PLANT WORLD 



western slopes of the Pinacate volcanoes near the Gulf of 

 California. Upon returning, the route was laid almost due 

 northward from Sonoyta to the Gila river, thus sectioning, 

 the great ridge at right angles. The results in detail will 

 form the subject of an extended paper now in preparation, 

 but some of the prominent features of the vegetation may 

 be discussed here with profit. 



The sahuaro, or giant cactus {Cereiis giganteiis) is 

 probably the most prominent by usefulness and obtrusiveness 

 of all the striking forms that inhabit the desert land of the 

 Papagoes. It ranges from the Tonto basin in central Ari- 

 zona westward to the Colorado ri\'er, which it crosses to 

 occupy a small area in California in the vicinity of the 

 mouth of the Bill Williams river. It extends to the east- 

 ward to the drainage of the San Pedro river and southward 

 in Sonora to the latitude of Guaymas, its exact limit not 

 being determiined, and follows close to the Gulf up to its 

 head. In the northern portion of its range, it occupies sunny 

 slopes at an elevation of 4000 feet and it descends into some 

 o{ the old craters of the Pinacate volcanoes to a point but 

 little above the sea-lev^el, climbing the main peak nearby 

 to the maximum elevation. As the limits of the range of 

 the sahuaro are approached, branching becomes less profuse 

 and the outlying individuals show simply columnar trunks, 

 usually bearing some marks of the stress under which they 

 exist. In more favorable localities an unending variety of 

 grotesquely arranged branches are to be seen and secondary 

 branches are exhibited in some instances. Native guides 

 are given to informing travellers, with apparent sincerity, 

 that the branches are in reality separate plants which have 

 risen from seeds deposited in cracks of the trunk by wood- 

 peckers and other birds. It has been pointed out recently 

 (Turrell, C. A., Univ. of Ariz. Monthly, Jan. 1908,) that 

 the common name of this great cactus [Cereiis giganteus) 

 must have been a Castilian rendering of an ancient name 

 in use when the Spanish explorers first came, and as the use 



