234 CLIMAX FORMATIONS OF WESTERN NORTH AMERICA. 



final stage more or less frequently. These relations have been indicated for 

 Colorado (Clements, 1904: 329) and have been suggested for the entire region 

 by Rydberg, who has also given a detailed account of the comparative dis- 

 tribution of the various species (1914: 459, 89; cf. also Cockerell, 1906: 861). 

 The aspects are less marked than in the prairie on account of the short season, 

 but there is a distinct difference between the earlier and later portions of the 

 growing period, in spite of the fact that a considerable number occupy the 

 mid-season. The distinction below is based upon the time when the species 

 begins to bloom, as well as the maximum of the flowering period. By far the 

 greater number of societies are mixed, and the order below is primarily that 

 of importance. 



Sieversia turbinata. 

 Mertensia alpina. 

 Rydbergia grandiflora. 

 Primula angustilolia. 

 Silene acaulis. 

 Achillea millefolium. 

 Castilleia pallida occidentalis. 

 Sibbaldia procumbens. 

 Androsace chamaejasme. 

 Artemisia scopulorum. 

 Arenaria biflora. 

 Oreoxis humilis. 

 Polygonum bistorta. 

 Pedicularis parryi. 

 Trifolium nanum. 

 Eritrichium argenteum. 

 Potentilla saximontana. 

 Campanula uniflora. 



Polygonum viviparum. 

 Campanula rotundifolia alpina. 

 Gentiana frigida. 

 Gentiana amarella. 

 Solidago humilis nana. 

 Agoseris aurantiaca. 

 Oreoxis alpina. 

 Saxifraga bronchialis. 

 Potentilla nivea. 

 Trifolium dasyphyllum. 

 Trifolium parryi. 



Vernal Societies. 



Lloydi serotina. 

 Cerastium arvense. 

 Allium reticulatum. 

 Salix reticulata. 

 Saxifraga nivalis. 

 Saxifraga flagellaris. 

 Saxifraga chrysantha. 

 Polemonium confertum. 

 Pseudocymopterus montanus. 

 Sedum roseum. 

 Erigeron uniflorus. 

 Draba aurea. 

 Draba streptocarpa. 

 Chionophila jamesii. 

 Androsace septentrionalis. 

 Dryas octopetala. 

 Phacelia sericea. 

 Zygadenus elegans. 



Estival Societies. 



Haplopappus pygmaeus. 

 Antennaria alpina. 

 Antennaria dioeca. 

 Salix nivalis. 

 Salix arctica. 

 Angelica grayi. 

 Arnica parryi. 

 Aster alpinus. 

 Erigeron leiomerus. 

 Phacelia lyallii. 

 Anemone narcissiflora. 



Erigeron compositus. 

 Erigeron radicatus. 

 Besseya alpina. 

 Ranunculus macauleyi. 

 Ranunculus nivalis. 

 Ranunculus eschscholtzii. 

 Thalictrum alpinum. 

 Phacelia alpina. 

 Phlox condensata. 

 Polemonium viscosum. 

 Primula parryi. 

 Douglasia nivalis. 

 Pedicularis lanata. 

 Pedicularis flammea. 

 Smelowskia calycina. 

 Trollius laxus. 

 Astragalus alpinus. 

 Myosotis alpestris. 

 Draba nivalis. 



Ranunculus adoneus. 

 Ranunculus pygmaeus. 

 Ranunculus hyperboreus. 

 Pedicularis scopulorum. 

 Pedicularis oederi. 

 Swertia perennis. 

 Pentstemon hallii. 

 Pentstemon glaucus. 

 Claytonia megarhiza. 

 Selaginella rupestris. 



THE SIERRAN ALPINE MEADOW. 



CAREX-AGROSTIS ASSOCIATION. 



Extent. — While the highest alpine peaks of the Pacific Coast are a little 

 higher than those of the Rockies, they are covered with permanent snow-caps 

 of great size, and the alpine zone is consequently much lower. In Washington 

 its best expression is found at 8,000 to 10,000 feet, and on Mount Shasta at 

 9,000 to 11,000 feet, though two species, Draba breweri and Polemonium 

 pulchellum, reach 13,000 feet. In the central and southern Sierra Nevada the 

 alpine meadows 'are best developed between 10,500 and 13,000 feet. The 

 lowest limit for the zone is found in the mountains of the upper Columbia 

 Basin, where it descends to 6,000 feet. 



