SCREW-PINES. 49 



bark of large trees, sending out roots as they ascend 

 which clasp around the trunk. Some mount straight 

 up, others wind round the supporting trunks, and their 

 large, handsome, and often highly-remarkable leaves, 

 which spread out profusely all along the stem, render 

 them one of the most striking forms of vegetation 

 which adorn the damper and more luxuriant parts 

 of the tropical forests of both hemispheres. 



Screw-pines. These singular plants, constituting the 

 family Pandanacese of botanists, are very abundant in 

 many parts of the Eastern tropics, while they are com- 

 paratively scarce in America. They somewhat resemble 

 Yuccas, but have larger leaves which grow in a close 

 spiral screw on the stem. Some are large and palm-like, 

 and it is a curious sight to stand under these and look 

 up at the huge vegetable screw formed by the bases of 

 the long drooping leaves. Some have slender-branched 

 trunks, which send out aerial roots ; others are stemless, 

 consisting of an immense spiral cluster of stiff leaves ten 

 or twelve feet long and only two or three inches wide. 

 They abound most in sandy islands, while the larger 

 species grow in swampy forests. Their large-clustered 

 fruits, something like pineapples, are often of a red 

 colour ; and their long stiff leaves are of great use for 

 covering boxes and for many other domestic uses. 



Orchids. These interesting plants, so well known 

 from the ardour with which they are cultivated on 

 account of their beautiful and singular flowers, are pre- 

 eminently tropical, and are probably more abundant in 

 the mountains of the equatorial zone than in any other 

 region. Here they are almost omnipresent in some of 

 their countless forms. They grow on the stems, in the 



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