480 GENERAL MORPHOLOGY OF PLANTS 



temperature at night, whereas during the summer in arctic 

 regions while the plants are growing there is continuous warmth 

 for growth and continuous light for photosynthesis. Five types 

 of alpine plants are recognized by some. First. Elfin tree. This 

 type has short, gnarled, often horizontal stems, as seen in pines, 



Fig. 423- 

 Polar tundra with scattered flowers, Alaska. (Copyright by E. H. Harriman.) 



birches, and other trees growing in alpine heights. Second. The 

 alpine shrubs. In the highest alpine belts they are dwarfed and 

 creeping, richly branched and spreading close to the ground, 

 while at lower belts they are more like lowland shrubs. Third. 

 The cushion type. The branching is very profuse and the 

 branches are short and touch each other on all sides, forming 

 compact masses (examples: saxifrages, androsace, mosses, etc.). 

 Fourth. Rosette plants. These are perennial, with short stems 

 and very strong roots, and play an important part in the alpine 

 meadows. Fifth. Alpine grasses. These usually have much 

 shorter leaves than grasses of the lowlands and consequently 

 form a low sward. 



