80 
mixed with P. pungens, Pseudotsuga, and Abies lasiocarpa (A. 
subalpina). Оп richer soil, there are almost pure stands of aspen, 
Populus tremuloides. On southern drier exposed ridges near the 
timber line Pinus aristata is at home. (4) Alpine zone, above the 
timber line, with the woody vegetation represented by low shrubs 
only. 
As stated above, Professor Harshberger has in one place in- 
cluded Arizona and New Mexico in the Rocky Mountain Region. 
I refer to pages 244—245, where he enumerates the trees of the 
Rockies. In this list which enumerates 63 species are included 
practically all the trees found in those two states.* In the list 
we find the following: Juniperus californica, J. virginiana, J. 
pachyphloea, Cupressus guadalupensis, Pinus chihuahuana, P. 
arizonica, Populus monolifera (P. deltoides), Morus microphylla 
(M. rubra), Juglans californica, J. rupestris, Condalia obovata, 
Olneya tesota, Parkinsonia Torreyana, Prosopis pubescens, P. juli- 
flora, Acasia Greggii, Platanus Wrightii, Chilopsis saligna (should 
have been C. linearis), Arbutus Menziesti, Cereus giganteus, 
Sapindus marginatus, Prunus angustifolia, Pyrus sambucifolia. 
Of these Juglans californica, Juniperus californica and Ar- 
butus Menziesii are Pacific Coast species; Cupressus guada- 
lupensis, Sapindus marginatus, Prunus angustifolia and Pyrus 
[now Sorbus] sambucifolia, Y have discussed before. For Popu- 
lus monolifera and Juniperus virginiana, eastern trees, should be 
substituted P. Sargent and J. scopulorum. АП the rest enu- 
merated above belong either to the desert regions of Arizona and' 
New Mexico or else to what Harshberger, on his map, has 
marked Western Sierra Madre. Rightly he extends this Mexi- 
* Some time after writing this article, I happened to read Gray and Hooker's 
n the Vegetation of the Rocky Mountains, and found that Harshberger's 
list is practically taken from that paper, he having omitted two species, added 
seven, and rearranged the order. Gray and Hooker acknowledged that they had 
compiled the list from Sargent's report in the roth United States Census. Much 
of what is here said of Harshberger's list, € as well to that of Gray and 
Hooker, and shows what errors even the best botanists may commit in compiling 
without sifting. The only differences between ач standpoint and that of 
Harshberger is that in their article they treated of the whole continental divide, 
and Harshberger had already limited the Rocky Mountain Region before giving 
the list, and that their article was published over 30 years ago. 
