66 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



CEREUS THURBERI Engelmann. 

 THURBER CACTUS; PITAHAYA; PITAHAYA DULCE. 



On the Boundary Line this huge plant ranges from the Sierra del 

 Cobota west to the Quitobaquita Mountains (Monuments Nos. 150 to 

 1T6). Its range does not extend far into the United States, probably 

 nowhere reaching the Southern Pacific Railroad. It bears an excel- 

 lent fruit, two crops ripening each year, in July and October. The 

 Papagos live on it exclusively. (Plate VIII, fig. 2.) 



CEREUS SCHOTTII Engelmann. 

 SCHOTT CACTUS; SINITA. 



This superb cactus was found only between the Sierra de la Salada 

 (Monument No. 175) and Monument No. 179. On most of this 

 stretch of country it was very abundant. 



The range of another giant cactus {JJereus pringlei) extends north 

 to within 40 miles of the United States border, south of the Sonoyta 

 Valley. 



OPUNTIA FULGIDA Engelmann. 

 CHOYA. 



This arborescent Cylindropuntia reaches the height of 3 meters, or 

 10 feet. It is abundant in southern Arizona. 



OPUNTIA VERSICOLOR Engelmann. 

 TREE CACTUS. 



The tree cactus is a striking feature of the scenery of Arizona and 

 Sonora, where it is locally abundant. 



OPUNTIA SPINOSIOR (Engelmann) Tourney 

 SIGURA. 



Locally abundant on the Sonora-Arizona boundary. 



ARBUTUS ARIZONICA (Gray) Sargent. 

 ARIZONA MADRONA. 



The madrona is a spreading tree, with reddish-brown rough bark. 

 It was found on the San Luis, Mule San Jose, and Huachuca moun- 

 tains, occupying a zone extending from near the junction of the 

 upper Sonoran and Transition nearly to the Canadian or lower 

 Boreal. Its ascertained vertical range is from 1,770 meters, or 5,800 

 feet (Millers Canyon, Huachuca Mountains), to 2,320 meters, or 

 7,600 feet (San Jose Mountains. Sonora, Mexico). Some remark- 

 ably fine examples of this tree were found near a spring in Turkey 



