50 INTRODUCTION TO BOTANY 
Lianas, which were mentioned in the preceding section, get 
their living without receiving from other plants any benefit 
except that of position. The other groups (2-5) are discussed 
in the following sections. 
50. Epiphytes. Unfortunately for students in temperate 
climates, flowering epiphytes are mainly confined to the tropics. 
The Spanish moss (fig. 31) is one of the few exceptions. A 
visit to any large greenhouse in which orchids are kept will, 
however, suffice to give a fair idea of the appearance of some 
Fie. 82. Indian pipe (Monotropa uniflora), a symbiotic saprophyte 
The plants are white from lack of chlorophyll 
of the most characteristic plants which live upon the trunks 
or branches of trees. Since these plants usually have little or 
no permanent water supply about their roots, they must be 
provided with means of absorbing water rapidly during rains, 
and of retaining it between one rainfall and the next. The 
Spanish moss, which is rootless, takes up water along the 
surface of the stems by the aid of special absorbent hairs 
which grow from the epidermis. This plant can become almost 
dried up without permanent injury. Other epiphytes, as 
orchids, have specialized water-absorbing tissues upon root, 
stem, or leaf surfaces, and from these tissues water escapes 
slowly in dry weather. 
