Prairie- and Sand Hill District. 533 
(= Lotus americanus), Pentstemon acuminatus, Pyrrhopappus scaposus, Cyperus acuminatus, Flav- 
eria angustifolia?). 
C. Foothill District. 
The foot-hill district extends northward through the Dakotas, Montana, 
Assiniboia and Alberta to its northern limit in Athabasca. On the south 
it extends along the mountains into Colorado and New Mexico. Physio- 
graphically it is a region of high, barren table-lands, broken by numerous 
canyons and dotted with frequent buttes. Floristically it is marked by the 
great number of mountain plants which here find their distributional 
boundary on the east”). One territory the Pine Ridge, is akin topographically and 
phytogeographically to the Black, Hills of South Dakota. In another territory the 
flora of the foothills represent an eastward extension of theflora ofthe Rocky Moun- 
tains. The trees of the foot-hills are not confined to the canyons as in the sand- 
hills but on the contrary grow on the hills and knobs of the mountains. 
They are Pinus ponderosa var. scopulorum, Funiperus scopulorum, $. virginiana, 
Populus monilifera (= P. deltoides), P. angustifolia, Ulmus americana, Celtis 
occidentalis, Fraxinus viridis (= F. lanceolata), Fraxinus pennsylvanica, Prunus 
americana, Acer glabrum, Negundo aceroides, Ostrya virginiana, Betula occiden- 
talıs and a rich assortment of shrubs®).. Three plant formations may be dis- 
tinguished, (1) the undershrub formation of table lands and bad lands, (2) the 
mat and rosette formation of buttes and hills, (3) the grass formation of high 
drairies and sandy plains. 
1. Undershrub Formations. 
The undershrub formation is not peculiar to the foothills of the prairie 
province; it here covers but a small area in comparison with vast stretches 
occupied by it in the Great -Basin. In the foothills, ‘this formation exhibits 
two: types, the one confined to high, somewhat grassy table lands, the other 
found solely on alkaline or bad lands. The former may be termed the sage- 
brush type, the latter the greasewood-white-sage type'). 
Sage Formation. (See plate XII of Artemisia frigida). This is named the 
sage-brush formation, because the westward species of Artemisia, chiefly 
A. tridentata, constitute the bulk of its controlling elements. In Nebraska, 
4A. tridentata, A. frigida, A. filifolia, A. cana and A. canadensis are found on 
the high plains and barren table-lands of the foot-hill region.  Bigelovia 
SER (2= Chrysothamnus nauseosus), Eurotia lanata, Gutierrezia euthamiae 
1) gerne M. A.: Characteristic sandhill Flora. Transactions Kansas Academy Science 
XI part I; 32— 
2) PouxD, ae and CLEMENTS, F.: The Phyto-Geography of Nebraska. 83. 
3) BEsSEY, CHARLES, E.: Annual Report Nebraska State Board of Agriculture 1900: 98—101; 
Darron, D. H.: Pine Ridge Timber. ı9th Report U.S. Geological Survey. 1897—98; Part, V.: 
387; RAMALEv, Francis: Wild Flowers and Trees of Colorado. 78 pages, 1909. 
) Pound, RoSCOE and CLEMENTS, F. E.: The Vegetation ine of the prairie Province. 
Botanical Gazette XXV: 
