4-8 THE GEOGRAPHY OF PLANTS. 



direction it was viewed. 31,668 tons of maho- 

 gany were imported into this country in 1848. 



But we must leave these gigantic denizens of 

 the forest, and survey some of the other aspects 

 of the vegetation of this zone. As in the woods 

 of our own country the bark of the trees is 

 covered with mosses and lichens, so the trees of 

 these tropical forests exhibit a profusion of the 

 most luxuriant and elegant forms ; splendid 

 parasites of the orchis tribe grow in the clefts 

 and crevices of the bark, with ilowers of the 

 most brilliant hues, and the greatest variety 

 of singular forms. The most elegant ferns, 

 (Polypodium, Hymenophyllum, and Tricho- 

 maneSj) climb up the trunks like ivy, or they 

 grow in tufts, which fasten on the branches, 

 and contrast in a peculiar manner with 

 the foliage. In the forests of the Philippine 

 Islands, a large handsome polypodium often 

 entirely covers a large part of the branch on 

 which it grows with its thick, bright brown, 

 scaly roots, and with its fronds, two or three 

 feet long, of a bright yellow colour, contrasts 

 most strikingly with the brown roots, and the 

 dark green foliage around. If any little spot 

 of the bark is left uncovered by these parasites, 

 it is fastened on by lichens, mosses, and junger- 

 nannise ; and some of the latter, of which it 

 requires the microscope to reveal the exquisite 

 beauty, grow upon the leaves of the other 

 parasites parasite upon parasite. 



But not only are the forest trees covered 

 with these splendid orchises, but a whole host 



