

[VOL. 2 



74 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Ranunculus glacialis, R. nivalis, R. pygmaeus, Sazifraga 



aizoides, 8. caespitosa, S. rivularis, S. stellaris, Silene acaulis, 

 Tofieldia borealis, Vahlodea purpurea, Veronica alpina, etc. 



V. THE LICHEN ZONE 



This embraces the often stony tracts above the preceding 

 zone, i.e., the highest mountain tops and the ground from 

 which they rise. 



Rocks and stones are here covered with the blackish yellow 

 Lecidea geographica and other lichens. Where there is a 

 little soil, some hardy mosses grow, and under favorable con- 

 ditions a very few species of higher plants. 



I may mention, as an illustration, that in 1877, when visit- 

 ing the mountain Haarteigen (5,546 feet) in Hardanger, i.e., 

 in the south of Norway, I noted the following higher plants 

 upon the comparatively flat top of the mountain: Carex 

 rigida, Luzula arcuata, L. spicata, Lycopodium Selago, Poa 

 alpina, Polygonum viviparum, Ranunculus glacialis, and 

 Rhodiola rosea. 



- 



As already repeatedly stated, all plant species are not 

 strictly confined to the zone under which they are mentioned 

 as especially characteristic factors. It is very general for 

 species somewhat to overstep the boundaries of their true 

 zone, either upward or downward. Certain species are even 

 found in all zones from the sea to the snow, since they have 

 a remarkable ability of adapting themselves to all kinds of 

 soil and to all kinds of climatic conditions. As instances 

 of such species we may mention Calluna vulgaris, Empetrum 

 nigrum, Eriophorum vaginatum, Festuca ovina, Nardus 



striata, Polygonum viviparum, and the species of Vaccinium. 

 Another circumstance is that typical mountain plants are 

 sometimes found in the lowlands right down to the sea, e.g., 

 in Jaederen, Alchemilla alpina, Arctostaphylos alpina, Bart- 

 schia alpina, Saxifraga aizoides, and Selaginella spinulosa. 

 Betula nana occurs in the southeast of Norway down to fifty 

 feet above the sea, and Dryas octopetala occurs at Lange- 

 sund and at Varaldso in Hardanger at sea-level. These occur- 

 rences were formerly often explained as relics of a previ- 



