PLANT ECOLOGY 327 



made mesopliytic. As contrasted with hydrophyte and xero- 

 phyte societies, the mesophyte societies are far richer in 

 leaf forms and in general luxuriance. The artificial soci- 

 eties which have been formed under the influence of man, 

 through the introduction of weeds and culture plants, are 

 all mesophytic. 



Among the mesophyte grass and herb societies are the 

 'arctic and alpine carpets," so characteristic of high lati- 

 tudes and altitudes where the conditions forbid trees, shrubs, 

 or even tall herbs ; " meadows," areas dominated by grasses, 

 the prairies being the greatest meadows, where grasses and 

 flowering herbs are richly displayed ; " pastures," drier and 

 more open than meadows. 



Among the woody mesophyte societies are the " thick- 

 ets," composed of willow, alder, birch, hazel, etc., either 

 pure or forming a jungle of mixed shrubs, brambles, and 

 tall herbs ; " deciduous forests," the glory of the temperate 

 regions, rich in forms and foliage display, with annual fall 

 of leaves, and exhibiting the remarkable and conspicuous 

 phenomenon of autumnal coloration ; " rainy tropical for- 

 ests," in the region of trade winds, heavy rainfalls, and 

 great heat, where the world's vegetation reaches its climax, 

 and where in a saturated atmosphere gigantic jungles are 

 developed, composed of trees of various heights, shrubs of 

 all sizes, tall and low herbs, all bound together in an inex- 

 tricable tangle by great vines or lianas, and covered by a 

 luxuriant growth of numerous epiphytes. (See Figs. 288, 

 289.) 



