12 PLANTS BAKERIAN.E. 



seems to have been formed by the sudden closing in of the 

 canon wall so that though not large it is of great depth. It 

 is as clear as crystal and even after our visit it still contains 

 some magnificent trout. The elevation here is about 9,000 

 feet and the hills and wet meadows near the lake yielded a 

 greater number of species than any other equal area that 

 we visited. In the water of the lake itself was an abun- 

 dance of Chara Hippuris and Potamogeton while on its 

 borders were Thalidrum alpinum, Gentiana heterosepala,Swertia 

 scopulina, Agastache wrticsefolia, Lilium montanum and many 

 other species not taken elsewhere. 



Mr. Tracy, who was the last to arrive, remained in the 

 neighborhood of Durango until July 28. Messrs. Earle 

 and Baker departed on the 18th and 19th respectively, 

 making about an even month in the field for each of the 

 three members of the expedition. 



Perhaps the most striking impression gained by the trip, 

 aside from that produced by the abundance and beauty of 

 the high alpine flora, is that of the distinctness with which 

 the different altitudinal floral zones are marked out and 

 limited. It is true a few species were found all the way 

 from the Mancos River bottoms at 7,000 feet to timber line 

 at 11,500 feet, but these instances are rare. In the great 

 majority of cases each species observed had an altitudinal 

 range of not to exceed 1,000 feet, even with similar con- 

 ditions of soil and moisture. In a general way these life 

 zones seemed to be the same here as in the not far distant 

 San Francisco Mountains of Arizona, where they have been 

 so carefully studied by Dr. Merriam, of the U. S. Biological 

 Survey. We could easily distinguish the pinon-cedar belt, 

 the pine belt, the aspen-spruce belt and the timber line belt 

 as designated by him, and we found this division a very 

 useful one in the prosecution of our work. 



