Chap. I] CHARACTERS OF THE TROPICAL CLIMATE 235 



genus Paepalanthus, essential constituents of the South American grass- 

 land districts ; and the Commclinaccac, belonging like the Eriocaulaceae 

 to the Enantioblastae, are very widely distributed particularly as species 

 of Commelina. 



Several monocotyledonous families that are most prominent in temperate 

 zones, such as Cyperaceae, Juncaceae, Liliaceae, Amaryllidaceae, are for the 



Fig. 123. To the left, Areca Catechu ; to the right, Ravenala madagascariensis. From the 

 botanic garden at Singapore. From a photograph by Kiikenthal. 



most part of merely subordinate importance, except for some not exclusively 

 tropical genera like Smilax, Agave, Fourcroya. 



Dicotyledones 1 . 



Dicotyledones preponderate considerably over Monocotyledones in the 

 flora of the tropics, and the number of their purely tropical families is much 



1 [The grouping of the families is that adopted in Strasburger's Text-book of Botany.] 



