244 Part II. Chapter 3. 
there appear masses of Arnica, the near relatives of which belong to higher 
altitudes followed by prairie species of Erysimum, Lithospermum, Petalostemon 
and in the autumn by Senecio and Gutierrezia. These species of the two. 
herbaceous autumn flora. The Senecio occurs regularly in the mon 
while Guzierresia is properly a plant of the plains. The flora of the lower’ 
foothills has been previously described. For the most part, the lower foothills 
are sparingly covered with pines. The north slopes of hills are better provided 
with trees than the south slopes. The herbaceous plants are chiefly those” 
previously mentioned as occurring on the mesas, or in the parks. The mout 
tain parks are somewhat level stretches of land encircled by high mountains, 
or hills. The altitude of these parks in the region under consideration 
migrate by way of narrow canyons, or else over the passes from 600° 
1500 feet higher. We, therefore, find a paucity of plants from lower altitu 
and relative abundance of proper mountain forms. Such plants, as Aguilegt 
coerulea, Potentilla (Dasiphora) fruticosa, Pentstemon secundiflorus , Epilob 
(= Chamanaerion), Eriogonum spp., Campanula spp., with species of As 
and Erigeron. In these parks and on the surrounding foothills, the conifer 
trees are the dominant plants, although here are found trees of Populus 
muloides. The coniferous trees are usually not in dense forests, but the park 
are open with the development of a rich grass flora. 
2. The forests adorning the mountain slopes require more extended deserip- 
tion, because we can use the present distribution of the trees and shrubs 
ascertaining the origin of the Rocky Mountain flora. Northward especially in. 
northern British America, the Atlantic and Pacific forests join and intermin; 
Southward with the Rocks Mountains trees are borne only on the mountaif 
and high plateaus and along the banks of streams descending from 
mountains. The mere botanic enumeration of the following species of 
gives no proper idea of the arboreal flora of the region. 
RER occidentalis Hook. Larix Lyallii Parlatore. 
californica Carr. Pinus edulis Engelm. 
» virginiana L. »  flexilis James. 
> scopulorum Sarg. » _ monticola Dougl. 
» pachyphloea Torr. »  aristataEngelm.(=P. alfourans 
Cupressus guadalupensis Wats. Wats.). 
Abies concolor Lindl. & Gord. »  chihuahuana Engelm. 
» subalpina Engelm. (= A. lasio- » albicaulis Engelm. 
carpa Hook.). | » Murrayana Engelm. = 
Pe Douglasii Carr, (= P. taxi- »  ponderosa Lawson var. scopu- 
folia Britt.). lorum Engelm. 
Picea Engelmanni Engelm. »  arizonica Engelm. 
» _pungens Engelm. Taxus brevifolia Nutt. 
Larix occidentalis Nutt,  Populus angustifolia James. 
