IV 



TROPICAL FLORAS 



59 



to, that number will be nearly or quite doubled when the 

 entire floras of Venezuela, the Guianas, Colombia, Ecuador, 

 and Peru are thoroughly explored. As, roughly speaking, 

 Brazil contains about half the great tropical forests of South 

 America, and allowing that its portion is the best known, 

 we may fairly add one-third of Spruce's lower estimate 

 (25,000) to its present numbers, which will bring the whole 

 to very nearly 40,000 species. By doubling this, we shall 

 reach 80,000 as the probable number of species existing in 

 tropical South America. 



As this number is considerably more than half the latest 

 estimate of the number of flowering plants yet known in the 

 whole world (136,000 species), 1 more than half of which 

 number will be absorbed by the comparatively well-known 

 temperate floras, it will be apparent that we have at present 

 a very inadequate idea of the riches of the tropical regions 

 in vegetable life. This result will be further enforced by 

 additional facts to be adduced later. 



I will here give a table of the few known statistics for 

 tropical America, which, though very fragmentary, will serve 

 to show the basis on which the preceding estimate of 

 probable numbers rests. 



Floras of Tropical America 



Note. — The number of Trinidad plants is from a Herbarium List 

 by Mr. J. H. Hart, F.L.S., Superintendent of the Botanical Gardens, 

 published in 1908. He states, however, that "a large amount of 

 material has not been arranged under natural orders," and that "the 



1 This number has been given me by Mr. W. B. Hemsley, Keeper of the 

 Kew Herbarium, as being that of Dr. Thonner in 1908. 



