imberbe, linbus Chamaemorus, Rubus arclicus, Cardamine macrophyllu, Ledum paliistre, 

 Drosera rotundi folia, Menyanthes trifoliata, Eriophoriim vaginaliim, Andromeda polifolia, 

 Ranunculus radicans, and Utricularia minor. 



In stony places and on dry, sloping cliffs I have collected as the most charac- 

 teristic plants: 



Agrimonia pilosa, Geranium Robertianum, Asplenium septenlrionale, Woodsia 

 ihensis, and Asplenium Rutd muraria. 



Fig. 35. Characteristic view south of the Algiac Pass near Ust 



Algiac. Picea obovata and Betula pubescens, with a dense ground 



vegetation consisting of various herbs (see text). 



The vegetation 



„,,,,..„ .,,.,. 11 r- • about the tree 



lowards the limit 01 tree vegetation the birch is generally iirst seen to remain ii„iit, 



behind, soon followed by the aspen. About 100 m. below the tree limit proper, the 

 spruce and the silver-fir also come to an end, only the cedar, the larch, and rarely, 

 the fir reaching it. The climatic conditions, especially the moisture, seem to be the chief 

 factors in determining which of these trees are to reach highest. In drier localities, as 

 for instance on the Tannu-Ola, the larch seemed to be the most persevering one, the 

 fir and above all the cedar, on the contrary, predominating in moister places, for in- 

 stance in the «AItaian». The height of the tree limit seemed, for the rest, to vary even in 

 rather neighbouring localities. It is also worth noticing that the tree limit descends east- 

 wards from the Yenisei from a height of about 2200 m. above sea-level to about 1700 to 

 1800 m. above sea-level near the Algiac Pass, a characteristic trait that has not yet been 

 accounted for. Moreover, the tree limit, of course, reaches higher on the south side of 

 the mountains than on the north when upon level terms in other respects. In the moister 

 parts of the Sayansk district the cedar is, as we have seen, the tree that climbs highest 

 up on the mountains, some stunted, weather-beaten specimens reaching high up to the 



59 



