= 
PENNELL—SCROPHULARIACEAE OF THE ROCKY MOUNTAINS. 3817 
map by the same author. The map covers the entire area of my 
study, but it is not based upon so full a field acquaintance and does 
not attempt the detailed zonal delineation which makes Cary’s map 
so valuable. However, in general terminology and broad limitation 
of zones I have followed it. 
The terminology used by Rydberg is in accord with that used 
abroad, and its names have more appropriateness than have those of 
Merriam, followed by Cary. <A third nomenclature has been evolved - 
by Mr. Marcus E. Jones in his studies of Utah vegetation. Appar- 
ently, Jones has reached the same conclusions as to the belts of 
vegetation to be recognized, so that his names may be correlated 
readily with those in current use. The three systems of zonal 
nomenclature are: 
RYDBERG. MERRIAM. JONES. 
Lower Sonoran. Lower Sonoran. Tropical. 
Upper Sonoran. Upper Sonoran. Lower Temperate. 
Submontane (Subboreal).! Transition. Middle Temperate. 
Montane. Canadian 
Subalpine. Hudsonian. \ Upper Temperate. 
Alpine. Alpine-Arctic. Alpine. 
The main point of divergence in which I follow Rydberg and not 
Merriam is in carrying the northern boundary of the Upper Sonoran 
Zone eastward and northeastward across the high plains following 
the divide between the Arkansas and Kansas river systems to the 
south, and the Platte drainage to the north. In the plains any 
zonal limit must be broad and more or less vague, but it certsinly 
seems to accord better with Penstemon distribution to recognize from 
this line northward an area of Subboreal plains than it does to com- 
mence such an areain Montana. Slighter divergence from Cary’s maps 
is in considering the Arkansas Valley above the Royal Gorge to be 
wholly Submontane (or Transition), with only some Upper Sonoran 
intrusion—at Salida I found only foothill Penstemons. The same 
treatment applies to the isolated Upper Sonoran areas or, as I view 
them, local Upper Sonoran intrusions into the Submontane Zone, 
above the canyon of the Grand River. 
Of botanical collections made within this total area there have been 
many, and yet, such is the diversity of the flora that with collections 
much more ample than those of many areas of the same size eastward, 
our knowledge of the flora is still much less complete. The best 
known sections are the foothills of eastern Colorado, especially those 
easily reached from Denver, Boulder, Fort Collins, or Colorado 
1 “Subboreal” applies to the Great Plains, ‘‘Submontane” to the mountains and 
intermontane plateaus. 
