250 OUTLINES OF PLANT LIFE. 



surfaces. These lateral organs take the place of leaves or of 

 lateral shoots, and are known as tendrils (figs. 69, 102). 

 (For their form see "If 99, 131; for their action, *{ 225, 251). 



354. 2. Clambering plants are those which form lateral 

 organs not sensitive to contact, and by means of them sup- 

 port themselves on adjacent plants. Recurved leaves, shoots, 

 and prickles (fig. 99) may serve these purposes. 



355. 3. Twining plants are those which have adapted their 

 shoots to winding about a support of suitable size. (See ^ 

 249.) 



356. 4. Root climbers have adapted their aerial roots to 

 attaching the plant to rough surfaces. (See ^82.) Such 

 structures are found only in fern worts and seed plants. 



357. 5. Epiphytes. — This name is rather loosely applied 

 to those plants which are attached only to other plants, though 

 they derive no food from them. All kinds of plants have 

 representatives in this group. Alga, diatoms, and other 

 small water plants attach themselves to other algae and the 

 higher water plants. Lichens, liverworts, mosses, ferns, 

 orchids, bromelias, etc., are abundant upon trees. Epiphytes 

 are attached by hair-like rhizoids, or by hold-fasts, which 

 apply themselves to the roughnesses or even penetrate the 

 outer dead parts of the supporting plant, but do not absorb 

 from the living tissues either water or food materials. The 

 water supply is provided for (i) by adaptations for absorbing 

 rain or dew, mists, or even dampness, instantly, either by the 

 surface, as in algae, mosses, and lichens, or by means of hairs, 

 as in the Spanish moss and other seed plants ; (2) by adap- 

 tations to catch the water in living or dead leaves and hold 

 it, either by capillarity or as a vessel, long after precipitation 

 has ceased. Many of the simpler epiphytes are adapted to 

 become dry without injury, while the larger ones are inhabit- 

 ants of moist tropical regions, where the danger of drying is 

 avoided and it is possible to obtain an adequate water supply. 



