. Bulletin. Natural history ; histoire naturelle -- Montana. BULLETIN 274 UNIVERSITÉ DU MONTANA presque pure forme les forêts. Près du haut des deux montagnes sous discussion, les lieux ouverts n'ont que les deux arbres alpins, le livre blanc de l'écorce et le pin, le sapin. Dans les bassins situés sur le côté est, toutefois, la con- ditions sont différents. Ici la neige est plus longue. L'écorce de pin blanc est rare ici, mais le sapin alpin fait mieux que sur les crêtes exposées. Dans les bassins il y a trois associations végétales. Sur les pentes abruptes où l'altération des processus sont souvent l'ajout de nouvelles roc

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. Bulletin. Natural history; Natural history -- Montana. 274 BULLETIN UNIVERSITY OF MONTANA form almost pure forests. Near the top of the two mountains under dis- cussion, the exposed places have only the two alpine trees, the white- bark pine and the alpine fir. In basins on the east side, however, the con- â ditions are different. Here the snow lies longer. The white-bark pine is infrequent here, but the alpine fir does better than on the exposed ridges. In the basins there are three distinct plant associations. On the steep slopes where the weathering processes are frequently adding new rock material, (Plate XLVII) the conditions are too strenuous for the existence of any plants. As soon as one of these talus slopes becomes stable enough, then plants begin to get a foothold, and finally trees may. Fig it. Portion of an alpine meadow, yotjo ft. altitude, Swan range, August, 190, 3. Photo, by M.J. E. appear. In places where the snow lies the year around, there is no vegetable life except the simple one-celled plant known as the "red snow." Bordering on these snow banks are the so-called alpine meadows. (Fig. 31.) They usually follow up the retreating snow and sometimes dog tooth violets, spring beauties, and anemones come up through the snow itself. Thus one can see these forms just appearing on the border of the snow field. At a little distance they are in full bloom, further away where the snow has disappeared earlier they have produced seeds, and still further from the snow they have finished their growth and have died down to the ground. It is usually in the latter places that one finds groups of trees, (Plate XLVII) nearly all alpine fir, for they appear where the snow first melts. Thus there is a relation between the plant societies found in these regions, and the time snow lies on the ground.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of the

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