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. 
