PHYSIOGRAPHY AND LIFE ZONES. 17 



second-grcwth pines over fire-swept areas, the groves of delicate 

 aspens scattered over the open spaces, and sturdy bhick cottonwoods 

 along the streams. In each area one species holds supremac}' and all 

 others take subordinate places. The lodgepole pine is the most 

 widespread and abundant tree, forming clear stands of slender poles 

 or smooth trunks of sawjog size over great areas. Engelmann spruce 

 is scattered over mncli of the park area and fills the Upper St. Mary 

 and Waterton Valleys with almost pure stands of tall, straight, and 

 graceful trunks. Balsams are generally scattered, but on some slopes 

 are the dominant trees. Hemlock, tamarack, cedar, yellow pine, and 

 western white pine are alj\mdant and variously mixed in the ^-al- 

 leys of the west slope of the park, where each in turn donunates its 

 favorite ground, while together they form the most superb forest area 

 of the park region. The scrubby but picturesque white-stemmed 

 pine (Pimis alhicaulis) of the timberline belt baffles the winds and 

 storms more successfully tlian any other tree, living and thriving 

 where beaten to the ground and held down by heavy winter snows 

 and fierce winds until it seems little more than a coniferous car]iet. 

 Engelmann spruce, the sulialpine fir, and the Lyell tamaraclc 

 also struggle up to timberline in dwarfed form, and sometimes 

 prove almost as hardj^ as the white-stemmed i^ine with which they 

 are associated. Many other trees find a foothold and fill minor places 

 in the forest. The Douglas spruce and limber pine, white fir, and 

 a few junipers are found at lower levels. The graceful white birch 

 on the west slope and the little brown western birch low down along 

 the streams with the mountain maple and alder and many of the 

 larger shrubs help to fill subordinate places. 



The shrubs and undergrowth of the forested and open areas include 

 manv useful, ornamental, and interesting species. Flowering shrubs, 

 as the syringa, ocean spray, mountain balm, and meadow-sweet, are 

 conspicuous. Fruit-bearing shrubs, as chokecherry, pin cherry, thorn 

 apple, serviceberry, elderberry, high-bush cranberry, mountain ash, 

 red raspberry, thimbleberry, blueberries of three or more species, 

 wild currants, and wild gooseberries, grow in greater or less profu- 

 sion. The western yew and devil's cluli add peculiar interest and 

 character to the shrubbery of the west slope, as do the ground cedar 

 and silver leaf to the east slope of the park. 



Even the ferns and club mosses and the real mosses and lichens in 

 great profusion and variety add their touch to the beauty and 

 interest of the plant life of the park as well as to the charm of the 

 forest and the rock shelves and shady cliffs of the mountains, Avhile 

 the least of all the visible plant life, the pink snow, gives a rosy 

 glow to the surface of the snow banks and glaciers, 

 51140°— 18 2 



