62 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



arroyos instead of upon their banks. It suckers profusely. We also 

 found it in arroyos about Tide Wells, and in canyons at the eastern 

 base of the Coast Range Mountains in California. It is known to 

 Mexicans as the " mangle." 



ROBINIA NEOMEXICANA Gray. 

 NEW MEXICO LOCUST. 



This beautiful locust grows in mountain canyons, ranging from 

 western Texas to Arizona. The largest are small trees from 3 to 4 

 meters (10 to 15 feet) in height, ripening their fruit in August. On 

 the San Jose Mountains. Sonora, Mexico, its range extends from 1.7-.7 

 to 2,021 meters (5,700 to 8,000 feet), or from the Sonoran to the upper 

 limit of the Transition zone. 



OLNEYA TESOTA Gray. 

 SONORA IR0NW00D; PALO DE HIERRO. 



This important tree of the Sonoran deserts ranges from the Sierra 

 de Moreno (Monument No. 146) to the Sierra de la Salado (Monu- 

 ment No. 17r>), on the Boundary Line, reappearing on the Colorado 

 Desert to the westward, where it is called " Arbol de Ilierro." It is 

 known in Arizona as the " Palo de Ilierro " and is a tree 6 meters (-20 

 feet) in height and half a meter (1\ feet) in diameter, with gray. 

 shaggy bark on the trunk and larger limbs, the young shoots being 

 bright green. The wood makes poor fuel and gives rise to a very dis- 

 agreeable odor when burning. Between the Sierra de la Salada and 

 la Represo, in which region this tree is generally distributed, though 

 largest and most numerous along the arroyos or dry watercourses, 

 the finest examples of the iron wood tree were seen. One of them 

 was three-fourths of a meter (2^ feet) in diameter and 10 meters (33 

 feet) in height. 



PTELEA TRIFOLIATA Linnaeus. 



HOPTREE. 



Several species of Ptelea were collected. On San Jose Mountains, 

 State of Sonora, Mexico, was found Ptelea s<m<-fti Greene and perhaps 

 /'. betulifolia; on San Luis Mountains was found /'. jueunda Greene, 

 a handsome species with chestnut-colored branches, while on Una 

 chuca Mountains /\ c<></)t</f// Greene is a common shrub. The leaves 

 of the last exhale a very powerful odor. 



HOLACANTHA EMORYI A. Gray. 

 HOLACANTHA. 



This was a large tree, west of San Bernardino River, near Monu- 

 ment No. T'.*. Mexican Boundary Line. 



