Chap. I] CHARACTERS OF THE TEMPERATE CLIMATE 423 



herbaceous, and to a certain extent quite essential constituents of grass- 

 land, of desert, and of the herbaceous flora clothing the soil of woodland. 

 The importance of Gramineae is everywhere recognized ; Cyperaceae and 

 Juncaccac are widespread ; Liliaceae, Amaryllidaceac, Iridaceae, and to a 



Fig. 234. Yucca arborescens in the Mohave desert, California. After Coville. 



less extent Ordiidaceae, are important constituents of the dry districts in 

 the warm temperate belts ; in the hotter parts of extra-tropical America 

 Bromeliaceae possess a few very common species, for instance Tillandsia 

 usneoides, and in Chili species of Puya. 



