108 The Plant World. 



blooming plants follow the snow line and the same species which 

 bloom in June on sunny southward slopes at timberline may be 

 found in August in the deep gulches north of the peak, where the 

 sun never shines. 



Even the casual observer notes that the meadows are cov- 

 ered with ring-like spots from two to six or even ten feet in 

 diameter. During the growing season these rings exhibit a 

 greener, ranker growth than the surrounding meadow, while 

 at other times they are conspicuous by reason of the reddish 

 color of the dried foliage. This peculiar appearance is due to 

 the species Sieversia turbinata. Examination shows that the 

 center of the ring is occupied by a more or less disintegrated 

 boulder, with often a stunted shrub or pine, whose usual habitat 

 is much lower. Probably the coarse rock fragments prevent 

 evaporation to some extent and the products of the disintegrating 

 granite supply an element of fertility to the soil. Thus the 

 area protected supports a larger growth and the lusty Sieversia 

 has crowded out its more adaptable companions, although it 

 very obligingly permits the harebells and a few individuals of 

 other species to inhabit the gravelly space within its ring. 



In the neighborhood of the saddle (altitude 12,600 feet) are 

 to be found some species whose normal habitat is near timber 

 line, for example, Penstemon stenosepaliis, Carduus scopulorum 

 and Chamaenerion angicstifoluim. Their presence here is easily 

 accounted for, however. The "saddle" is a depression between 

 the main mass of the peak and the spur known as Sachett 

 Mountain. 7he warm air from below, rising along the sides of 

 the mountain, finds here the first crossing point, and so there is a 

 continual current of air passing over the saddle from below and 

 such seeds as are easily carried by the wind are borne aloft and 

 deposited here. The area is well watered by seepage from the 

 hills on each side and the temperature is probably moderated 

 a little by the ascending air currents so that these plants mature 

 their blossoms in favorable seasons. I doubt whether the seeds 

 ever mature where the frosts come so early, but the colonies are 

 kept from extinction by yearly deposits of seeds from below. 



Spring, summer and autumn are quite distinct. Spring 

 is characterized by the blooming of such species as Thlaspi 

 coloradense and Eritrichium argenteum, which require" but a 



