Epiphytism 669 



the somewhat circular leaves are covered with long glandular hairs 

 ("tentacles") which secrete a sticky substance to capture insects. The 

 tentacles bend toward the center to form a trap in which the enzymes 

 digest the insect. There are approximately two hundred species of 

 chlorophyll-bearing, angiospermous plants which are insectivorous or 

 carnivorous. They photosynthesize their foods but supplement with cer- 

 tain essential elements by the digestion of insects. If the correct ingredi- 

 ents are present in the soil, they need not ingest the animal foods. In the 

 so-called bladderwort plants, present in ponds and lakes, there are tiny 

 "bladder traps" on the submerged stems. Each bladder has a one-way 

 trap door through which aquatic animals enter and in which they are 

 digested. The leaves of Venus's flytrap and certain pitcher plants are 

 able to digest such foods as hard-boiled ^gg, meat, etc. 



VII. EPIPHYTISM 



Epiphytes (ep'ifite) (Gr. epi, upon; phyton, plant) are plants which 

 use other plants, poles, trees, wires, etc., for support but do not derive 

 nourishment from the other plant; hence they are not parasitic. Epi- 

 phytes are primarily autotrophic (o to -trof ik) (Gr. auto, self; trephein, 

 to nourish) which means they photosynthesize their food and do not get 

 it from plants on which they may happen to be attached. They secure 

 carbon dioxide and water from the atmosphere and moisture and nu- 

 trients from debris in crevices in which they may be anchored. Ordi- 

 narily, epiphytes take no sustenance from the plant on which they are 

 attached, but they may injure the plant by shading the leaves, by break- 

 ing limbs because of excessive weight, etc. 



Certain algae may be epiphytes on other plants. The green alga Proto- 

 coccus may grow epiphytically on the bark of trees. Certain brown algae 

 and marine red algae may grow on other algae as epiphytes. Certain 

 species of algae even grow among the hair of the three-toed sloth. Cer- 

 tain species of lichens, mosses, ferns, and tropical orchids and certain 

 members of the pineapple family may be epiphytes. "Spanish moss" 

 {Tillandsia) of the South is an epiphyte which is a rootless, flowering 

 plant of the pineapple family and which hangs in great masses from 

 trees, poles, and wires (Fig. 331) . Often the growth is so enormous that 

 the tree is killed, even though the "moss" is not parasitic. The flexible 

 internal filaments of Spanish "moss" are being used for commercial pur- 

 poses. 



