Mat, 1890.] SHRUBS OF THE DEATH VALLEY EXPEDITION. 287 



times, particularly after rains, is so powerful as to cause pain in the 

 nostrils. 



In addition to the sage, many of the desert ranges support a growth 

 of shrubs and small trees rarely if ever found on the intervening 

 deserts and plains, whatever the altitude. This seems to be due in 

 part to increased moisture and in part to the physical character of the 

 slopes. The so-called cedar (Juniperus californica utahensis) and the 

 pinon or nut pine (Pinus monophylla) clothe the summits and higher 

 slopes of many of the ranges, forming stunted open forests of much 

 beauty. Mixed with these are scattered clumps of bushes represent- 

 ing a number of genera, most of which bear green foliage and hand- 

 some liowers. Conspicuous among them are Berberis fremonti, Geano- 

 tkus fremonti, Rhus trilobata, Robinia neomcxicana, Gercis occidentalism 

 Primus fasciculata, Kunzia tridentata [until recently known as Pur- 

 shia], Gowania mexicana, Fallugia paradoxa, Amelanchier alnifolia, 

 Peraphyllum ramosissimum, Garrya veatchii flavescens, and Symphori- 

 carpos longifolius. Scrub oaks of two species (Quercus gambelii and Q. 

 undulata) are common in places ; the green Ephedra viridis is almost 

 universally present, and the mescal {Agave utahensis) occurs on a few 

 of the slopes. 



Some of the desert ranges, as the Funeral Mountains, are too exces- 

 sively hot and arid to support even these forms of vegetation; others, 

 as the Charleston Mountains, push their lofty summits into so cold an 

 atmosphere that they obtain a covering of the boreal pines and firs. 

 These higher mountains, when rising from the Lower Sonoran deserts, 

 present in succession all the extra tropical zones of North America, 

 which, from their close juxtaposition, may be here studied to unusual 

 advantage. 



In ascending or descending such slopes the change from one zone to 

 another is quickly recognized and the altitude of first appearance of 

 the various new species encountered may be recorded with considera- 

 ble confidence. Not so, however, with the species lost, for, except in the 

 case of trees and such strikingly consincuous forms as the yuccas, some 

 of the cactuses, the creosote bush (Larrea), and a few others, it is ex- 

 ceedingly difficult to detect the disappearance of species when passing- 

 out of their ranges. A close parallel occurs in the study of bird migra- 

 tion. Every observer reports the first appearance of the newcomers in 

 spring,*while but few have any record of disappearance in autumn. 



In order to make sure of the upper and lower limits of species on a 

 mountain side the same line should be traversed both up and down the 

 slope, which it was impossible to do in the limited time at our disposal. 

 In cases where this is done the resulting altitudes relate to a particular 

 slope only and too often to a canon or wash on that slope, so that they 

 can not always be accepted as fair averages for the base level and slope 

 exposure to which they properly pertain. 



Most of the altitudes were determined by aneroid barometer and are 



