494 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



to Sierra Madre rather than to the Rockies, it will not be discussed 

 here. 



The eastern representative of the Upper Sonoran Zone is the 

 wooded division of the Upper Austral Zone or the Carolinian Zone. 

 This is also characterized partly by evergreen forests of conifers, 

 as the short-leaved pine, partly of deciduous broad-leaved trees, 

 as rose-magnolia, tulip-tree, persimmon, hickory, oak, and walnut. 

 The live-oaks seem lacking. This zone corresponds to the Medi- 

 terranean region with evergreens of both classes, as pinons, 

 cypresses, and junipers, as well as live-oaks, olives, laurels, etc. 

 The true prairies are probably the grass-covered portion of this 

 zone in the Middle West. 



2. Staked Plains 

 These are discussed already under the Great Plains. 



3. Great Basin 

 The Great Basin comprises the larger part of Utah and Nevada, 

 northern Arizona, southern Idaho, and small parts of New Mexico, 

 Colorado, Wyoming, Oregon, and California. In it is included 

 the Great Basin proper, without outlet, and the upper basins of 

 the Colorado of the West and Snake River. The flora of the 

 basin is a desert flora, characterized by such shrubs as Atriplex 

 confertifolia and other species of that genus, Artemisia tridentata 

 and its relatives, Sarcohatus, Graya, Tetradymia, Yucca, and num- 

 erous species of Eriogonum (both shrubby and herbaceous). 



4. Columbia Plains 



These I have not visited personally and shall only refer to the 

 description in Piper's Flora of Washington. 



\'l. Lower Sonoran Zone 

 The Lower Sonoran Zone consists mostly of desert lands. The 

 woody vegetation is characterized by the Creosote Bush (Covillca), 

 mesquites (Prosopis), acacias, cactuses, yuccas, and agaves. In 

 the Middle Pro\ince, it may be divided into two di\isions, the 

 l\'xanf)- Mexican Regi(jn east of the mountains, and the true 

 Sonoran Region wc-sl thc-reof. The former send up two tongues 

 northward along the \ allc\s of (he Rio (^irandr and the Pecos, 



