64 



So much has been written regarding the vegetation of the 

 Tucson region* that it is hardly necessary to attempt any account 

 in this connection. During their five days' stay here the members 

 of the party were royally entertained, practically every expense 

 being defrayed by the Carnegie Desert Laboratory. Never had 

 the writer realized that a desert could be such a congenial habitat. 

 The first day was occupied by an examination of the laboratories 

 and their environs. On the second the excursionists were driven 

 in automobiles eighteen miles across the desert to the foot of the 

 Santa Catalina Mountains. That night they encamped in the 

 midst of a grove of oaks and junipers 2,500 feet higher and 30 

 degrees colder than the distant plain. From this base camp 

 trips were made to higher levels. All of the party climbed to 

 Bear Canyon (altitude 6,000 feet) and several ascended Mount 

 Lemmon (altitude 9,150 feet). 



Two days at the Grand Canyon marked the culmination of 

 the I. P. E. From a standpoint of botanical interest the most 

 noteworthy feature here is the zonal distribution of the vegeta- 

 tion on the sides of the canyon. At the top is an open, park-like 

 forest of Pinus ponderosa, P. edulis and Juniperus monosperma. 

 Immediately below the rim occur Pseudotsuga and Abies con- 

 color, but farther down these are superseded by pinyon and 

 juniper. About halfway to the bottom of the canyon is a plateau 

 covered with an almost pure growth of Coleogyne ramosissima, 

 while at the level of the river vegetation is scant and extremely 

 xerophytic, Ephedra sp. being the most characteristic plant. 



Stops for study in the pine forests of eastern Texas and in the 



region about New Orleans had been contemplated, but extensive 



floods made it necessary to abandon this part of the program. 



At New Orleans the party disbanded, most of the European 



members returning to New York via Washington. 



Sheffield Scientific School, 

 Yale University 



* See especially Spalding, V. M. Distribution and movements of desert plants. 

 Carnegie Inst. Publ. No. 113, pp. 1-144. pi. 1-31- 1909. 



