of the Rocky Mountains. 233 
moisten with their spray such choice plants as Mertensia Sibirica, 
Cardamine cordifolia, Saxifraga estivalis, and a most elegant and 
conspicuous Primula (811) near P. nivalis. 
In mounting up the steep ridges which border their course, to 
Teach their alpine sources, the view of the surrounding country 
: 1s entirely shut in by the heavy growth of pines, including on 
the higher ridges and abrupt slopes, Pinus contorta with its slen- 
der tapering trunk and stiff scanty foliage; while on more level 
spots, or occupying depressed basins forming sub-alpine marshes, 
Abies alba and Abies balsamea shoot up their tapering spires. The 
usual undergrowth in these pine woodsis composed of Vaccinium 
Myrtillus, Shepherdia argentea, Berberis Aquifolium, Pachystima 
Uyrsinites, &e. 
bl 
In moist springy places and along the borders of marshes we 
find Gaultheria Myrsinites, Pedicularis surrecta, Senecio triangula- 
ms, Mitella pentandra, Habenaria dilatata, Pyrola rotundifolia, var. 
wmosa, &. As a rarity, in scattered localities, we here meet 
with the charming Calypso borealis. Sis 
On approaching the limits of arborescent growth, indicated at 
first by a stunted appearance of the common varieties of pine, 
las the more frequent occurrence of the alpine species, P1- 
nus flexilis, we at length come somewhat abruptly upon open 
stretches, characterized by their peculiar vegetation and general 
spect as truly alpine. Some few trees straggle for a variable 
: toi t rocky slopes, but in these situations they 
er exhibit the severity of the exposure by deformed and 
Sted trunks, often nearly prostrate, and showing by a uniform 
bending of their upper branches the direction of prevailing 
Tee winds, and the weight of wintry snows. 1hese arctic 
forms are confined almost exclusively to a single species of pine, 
heretofore undescribed, (Pinus aristata, Engelm.) belonging to 
the same group as Pinus flexilis, James. 
Beyond this there is a succession of alpine exposures, charac- 
the y extensive patches of snow scattered irregularly over 
-20untain slopes, generally indicating the accumulation of 
drifts ; being most abundant and persistent in recesses near the 
higher elevations, At other points a rough talus of rocks is 
*tivable sha d loosel regated, formi 
sures. In Ht Scindaite Pinca singe Siberian squirrel findsa | 
break the solitude of these 
ied out b 
ed snow-banks with lower alpine brooks. Among these 
AM. Jour. Scr.—Szconp Serres, Vou. XXXII, No. 98.—Marc#, 1962, 
30 
