PLANT SOCIETIES 
369 
Indian Pipe. This plant, although it produces flowers 
and seeds, has no chlorophyll and so is a waxy white in 
appearance. It gets its nourishment from decayed organic 
matter, usually wood, just below the soil. A fungus which 
grows on the roots helps them to absorb this prepared food 
(see Figure 268). 
Mistletoe. — We are most familiar with this plant as a part 
of our Christmas decorations. Mistletoe has chlorophyll 
and so is able to manufacture its own food, but it has no 
roots for absorbing water, making it dependent on a larger 
plant for this necessary part 
of its vital conditions. The 
plant possesses absorbing or¬ 
gans which pierce the bark of 
the trees upon which it grows. 
As a result it does much in¬ 
jury to the trees by using the 
water which they need for 
their own life processes. In 
the South the mistletoe is 
regarded as a great pest. 
312. Movements of Plants. 
— Most plants move slowly 
and only in response to one 
of several stimuli. Touch, 
or contact, is the stimulus in the case of sundew and Venus’s 
flytrap, both of which are peculiar in moving quickly. 
Tendrils curve under the influence of the same stimulus, 
but they move slowly. 
313. Plant Societies. — The term plant society is applied 
to any collection of plants which grow under similar con¬ 
ditions. The trees of the forests, and the grass and weeds 
of our lawns, are typical examples. In most cases water, or 
the lack of it, is the basis for classifying or grouping plants 
in societies. Some plants, e.g., many algae, live submerged 
Figure 342. — Cross Section of 
Leaf of Desert Plant. 
Note the very thick layer of 
cutin (A)‘, the epidermal cells, also 
cutinized ( B) ; the short, incomplete 
layer of palisade cells (C); and a few 
cells of the spongy layer ( D ). Com¬ 
pare with Figure 263. 
