276 EVOLUTION OF PLANTS 
These tropical epiphytes represent many families of 
flowering plants and also include a large number of 
ferns. One family of the latter, the exquisite filmy- 
ferns (Hymenophyllace), are mainly epiphytic, and one 
of the most charming sights of the tropical mountain 
forests is exhibited by the trunks and branches of the 
trees, covered with the dark-green, finely cut fronds of 
these dainty ferns. In these dark forests, reeking with 
moisture, everything is covered with a mass of epi- 
phytic growths, even the leaves near the ground being 
overgrown with lichens and creeping liverworts. 
Of epiphytic flowering plants there may be recognized 
two categories — the lianas, or creepers, which, at first 
at least, are rooted in the earth, but may later, by de- 
veloping aerial roots, become truly epiphytic; secondly, 
the true epiphytes, or “air plants,” such as many or- 
chids and Bromeliacez, like the “Spanish moss,” which 
never are connected with the earth. These air plants 
abound everywhere in the tropical forests, and some of 
the epiphytic orchids are among the most beautiful 
of all plants. These showy species are, however, 
in a minority, as most of the tropical orchids are 
by no means conspicuous. The peculiarly Ameri- 
can family, the Bromeliacee, includes a large num- 
ber of curious epiphytes, some of which are showy 
plants with spiky leaves and large clusters of bril- 
liantly colored bracts or flowers. The best known 
of these is the “Spanish moss,” of the southern 
United States, but most of them are strictly tropical 
in their range. 
Many species of Ficus, or fig, are epiphytic, while 
still others begin as epiphytes, germinating upon the 
