10 
MUSEUM BULLETIN NO. 26. 
As mentioned above, the vegetation of the southern part of the 
third prairie steppe is decidedly xerophile. As a result, a number of 
species occur which approach desert types in being, in some way or other, 
protected against rapid transpiration. Such plants are: Eriogonum 
flavum, Eurotia lanata , Opuntia polyacantha, Mamillaria vivipara, Potentilla 
Hippiana , Oxytropis splendens , Linum rigidum , Plantago Purshti , Aplo- 
pappus spinulosus, Artemisia frigida, A. cana , A. Ludoviciana , Senecio 
canus , Iva axillaris , Lygodesmia juncea , and others. 
Of other plants, characteristic of the southern part of the third 
prairie steppe, the following may be mentioned: Bouteloua oligostachya, 
Munroa squarrosa, Schedonnardns paniculatus , Oryzopsis hymenoides, 
Stipa spartea, S.comata,Sporobolus Richardsonii, Calamagrostis americana, 
Danthonia intermedia , Agropyron dasystachyum, Zygadenus chloranthus , 
Rumex venosus, Oxybaphus hirsutus , Ranunculus cardiophyllus , Polanisia 
trachysperma, Chamcerhodos erecta , Oxytropis Lambertii , Hedysarum 
Mackenzii , Potentilla flabelliformis, Heuchera hispida, Linum Lewisii, 
Malvastrum coccineum , Oenothera triloba , 0. serrulata , 0. pallida , Gaura 
coccinea , Solanum triflorum, Pentstemon acuminatus, P. procerus , 
Orobanche fasciculata , Liatris punctata, Gutierrezia Saro throe, Chrysopsis 
villosa , Solidago missouriensis, S . rigida, Aplopappus lanceolata, A. 
acaulis, Townsendia exscapa, Aster angustus, Erigeron coespitosus, E. 
pumilus , Antennaria aprica, Helianthus petiolaris , H. giganteus, Gaillardia 
aristata. Arnica pedunculata , Senecio integerrimus, Cirsium Drummondii , 
Lactuca pulchella. 
Rocky Mountain Foothills. — A great number of prairie species 
reach a considerable altitude in the foothills of the Rocky Mountains. 
On the other hand, a number of sub-alpine forms descend practically 
to the prairie, the result being that at the base of the foothills, 
where the two types of floras intermingle, the vegetation is very rich 
in species. As the foothills are ascended the prairie forms gradually 
disappear and are replaced by mountain species. The vegetation in 
general becomes more luxuriant in appearance, the herbaceous plants 
grow taller, shrubs begin to form an important feature in the flora and 
real forests are established. Besides typical mountain and prairie forms, 
the following species may be considered as characteristic of the foothills : 
Stipa Richardsonii , Avena striata , Bromus Porteri , Elymus dasystachys , 
Eriogonum subalpinum, Arenaria capillaris , Aquilegia brevistyla, Delph- 
inium glaucum, D. Menziesii , Thalictrum occidental, Actaea arguta, 
Parnassia montanensis , Spiraea lucida, Oxytropis viscidulus, Hedysarum 
sulphur escens, Geranium Richardsonii, G. incisum, Epilobium latifolium, 
Angelica Dawsoni, A. Lyallii, Carum Gairdneri, Primula americana, 
Lappula fioribunda, Castilleja species, Lonicera glaucescens, Aster con- 
