79(3 Lloyd, The Desert Botan. Laboratory of the Carnegie Instit. of Washington. 



small tree is the palo verde (Parkinsonia mwrophytta) but we find 

 intermingled with it a Celtis, a Lycium, and more notably, the 

 ( K-otillo {Fouqiäeria splendens). In the .spring' the whip like branches 

 each bears a mass of scarlet flowers, and make a gorgeous .show. 

 Of the still smaller shrubby growths are, more prominently, the 

 Franseria and an Encelia, both furnished with woolly leaves. The 

 latter makes in the month of April a splendid mass of yellow 

 flowers. These are of course sup})lemented by very numcrous 

 annuals and smaller perennials. Several species of cacti, in addition 

 to the above are present. Two species of flat-stemmed Opuntia, 

 and an arborescent type, Opuntia versicolor, a small Mamillaria, a 

 small Cereus (C. Fendleri), with fine magenta flowers, and a barrel 

 Cactus, Echinocacttts Wislezeni, are the chief. Other localities aff'ord 

 numcrous other species, but I have mentioned these few merely 

 to suggest the richness and general character of the flora. 



The distributional relations of this Vegetation may be indicated 

 in a general way by the following data, kindly supplied to me by 

 Professor V. M. Spalding. Within the boundaries of the Labo- 

 ratory reservation there are 146 genera and 195 species of these 

 genera, 70 are world wide in their distribution, while 34 are com- 

 mon to N. and S. America, 19 of these following the Cordillera 

 north and south. Of the lot, 28 are limited to Arizona and adja- 

 cent territory, or extend along the mountains of western N. A. Of 

 the species, 168 are restricted to their speculiar area in Arizona 

 and adjacent territory. 13 wäre idely distributed in n. A., 7 are 

 common to N. and S. America, while only three, aside from intro- 

 duced weeds, are found in the eastern and western hemispheres. 



The whole area of ground which pertains to the Laboratory 

 covers 860 acres, all of which is now fenced in and thus protected 

 from damage by animals. The area includes a stretch of mesa cut 

 by a "wash" tljat is a small stream bed usually dry, excepting 

 during heavy rains, and, for the major portion, of the volcanic 

 foothills on which the building Stands. 



I append a summary of the work which has thus far been 

 carried on at the Desert Botanical Laboratory by those who have been 

 officially connected with it during the period up tili the present tinie. 



Dr. MacDougal has been engaged in field work and explo- 

 rations in the American deserts for the U.S. Government and for 

 the New York Botanical Garden since 1891. Since, Ins connection 

 with the Desert Laboratory he has cooperated with Mr. F. V. Co- 

 ville in a general geographica! study of the North American Deserts, 

 and has devoted special attention to the arid regions about the head 

 of the Gulf of California in which opportunity has been taken to 

 make some general comparisons betwen the mesophytic Vegetation 

 of the delta of the Rio Colorado, and the adjacent deserts. One 



