jo6 



ZONES AND REGIONS [Pt. Ill, Sect. IV 



Alps, for instance, they scarcely exceed that of species of Grimmia and 

 Barbula, which in Central Europe represent the cushion-form on walls and 

 rocks ; others again resemble masses of coral, as in the case of the New 

 Zealand species of Raoulia and the Andine species of Azorella, the velvety 

 smooth and solid cushions of which attain a height of two meters, and are 

 composed of densely-packed prismatic shoots. 



4. Perennial rosette-plants (Figs. 410-414) play a leading part, especially 

 on alpine meadows. They are distinguished from similar plants of the 

 lowlands by much shorter epigeous shoots and much longer and stronger roots. 



5. Alpine grasses usually have shorter leaves than those of lowlands, so 



Fig. 408. Alpine flora of New Zealand. Dwarf-shrub. Coprosma cuneata, Hook. f. 



Natural size. 



that alpine grassland possesses a low sward. In the tropics these grass- 

 leaves are constructed on the steppe type — narrow, rolled up, stiff, setaceous — 

 whilst in high latitudes they are often true meadow grasses. 



Leaves, at least in the higher parts of the alpine region, are provided 

 with pronounced protective measures against transpiration. In woody plants 

 they are usually leathery, in perennial herbs, in accordance with the great 

 dryness of the air that sometimes prevails, they are often very hairy. Gla- 

 brous perennial herbs have thick, often succulent leaves, a strongly-developed 

 cuticle, narrow intercellular spaces, and the strong development of palisade- 

 cells that is common in xerophytes. 



The flowers of alpine plants usually possess bright colours, and in species 

 that also frequent the lowlands there is a distinct tendency for the colours 

 to be better developed in the alpine region. In many cases the flower is 



