IV 



TROPICAL FLORAS 57 



the entire tropical portion from South Mexico to Panama 

 commonly known as " Central America " ; and in South 

 America the vast areas of Brazil, itself comprising more 

 than half of tropical South America. The comparatively 

 easy access to this latter country, the attraction of its gold 

 and diamond mines, its extensive trade with England and 

 with other civilised countries, have all led to its being 

 explored by a long series of botanists and travellers, the 

 result of whose labours have been incorporated in a monu- 

 mental work, the Flora Brasiliensis of Martius, recently 

 completed after more than half a century of continuous 

 labour. 



The number of species described in this work is 22,800, 

 an enormous figure considering that its area is less than half 

 that of tropical Africa, and that probably two-thirds of its 

 surface has never been thoroughly examined by a botanist. 

 The Central American flora, as described by Mr. Hemsley, 1 

 in less than one-third of the area of Brazil has about 12,000 

 species, and this is no doubt a much nearer approach to its 

 actual numbers than in the case of Brazil. 



As regards the additions that may yet be made to that 

 flora, and especially to the great forest region of adjacent 

 countries, I will quote the opinion of a very competent 

 authority, the late Dr. Richard Spruce, who assiduously 

 studied the flora of the Amazon valley and the Andes for 

 fourteen years, and himself collected about 8000 species 

 of flowering plants, a large proportion of which were forest- 

 trees. In a letter to Mr. Bentham from Ambato (Ecuador), 

 dated 22nd June 1858, he writes: "I have lately been 

 calculating the number of species that yet remain to be 

 discovered in the great Amazonian forest from the cataracts 

 of the Orinoco to the mountains of Matto Grosso. Taking 

 the fact that by moving away a degree of latitude or 

 longitude I found about half the plants different as a basis, 

 and considering what very narrow strips have up to this 

 day been actually explored, and that often very inadequately, 

 by Humboldt, Martius, myself, and others, there should still 

 remain some 50,000 or even 80,000 species undiscovered. 



1 See Biologia Centrali Americana, by Messrs. Godman and Salveri ; Botany, 

 4 vols., 1 888. 



