THE EPIPHYTES 155 



by curiously developed hairs on their leaves. 

 Examples of this habit are afforded by the 

 Tillandsias, and other Bromeliads of the 

 tropical forests of the Western world. The 

 roots may be altogether lacking in some species, 

 and even when they are produced they merely 

 serve to attach the plant to a branch, and 

 function only slightly, or not at all, as water- 

 absorbing organs. Tillandsia usneoides, com- 

 mon in the damp West Indian forests, pos- 

 sesses no roots ; it bears sickle-shaped leaves 

 which readily become entangled in small 

 twigs, and the greyish-green festoons of this 

 plant, as they hang down from the branches, 

 resemble luxuriant lichens rather than a 

 flowering plant. Indeed, the resemblance is 

 so great as readily to deceive any but a care- 

 ful observer. 



The epiphytic tillandsias absorb the whole 

 of their water supply through remarkable hairs 

 which clothe the surfaces of the plant. The 

 accompanying figure illustrates their general 

 appearance and structure (Fig. 20). From a 

 slight depression there arises a stalked hair, 

 the upper portion of which is flattened out 

 as a membranous expansion consisting of 

 many cells arranged around the central group 

 that terminates the stalk. The cell walls 

 on the upper surface of the hair are very 

 thick, but they are practically destitute of 

 a cuticle, and water probably can pass 

 through them as well as through the walls 

 on the under surface which are much thinner. 



