CHAPTER VIII 
ROOTS 
General Features of Roots 
The higher plants consist of roots and shoots. The roots are 
generally underground structures, while the shoot is the aérial 
portion consisting of the stem with its leaves, buds, flowers, and 
fruit. Plants like the Algae, which live in the water where all parts 
of the plant can absorb directly from the surroundings, do not 
need roots, although they often have structures known as hold- 
fasts which anchor them; but holdfasts are too simple in struc- 
ture to be called roots. Even in the Mosses, which are mainly 
land plants, instead of roots there are hair-like structures, called 
rhizoids, which anchor the plant to the substratum. True roots 
are complex structures and are characteristic of Ferns and Seed 
Plants. 
Although we think of roots as underground structures, there 
are, however, a few plants having roots adapted to living in other 
situations, as in the water, air, or the tissues of other plants. 
But with few exceptions our cultivated plants depend upon soil 
roots, which, therefore, deserve most attention. 
Being underground structures, soil roots normally arise from 
the stem’s base, from which they radiate by elongating and grow- 
ing new branches, which in turn branch and rebranch until the 
soil about the plant is quite thoroughly invaded by its root sys- 
tem. Usually a plant’s root system, tapering into numerous 
branches almost hair-like in size, is more branched and spreads 
farther horizontally than its stem system. The profuseness 
with which roots branch is well shown by the estimated root 
length of some plants. Thus the length of all the roots of a single 
Wheat or Oat plant, laid end to end, is estimated at 1600 feet, or 
more than a quarter of a mile. For a vigorous Corn plant the 
estimated root length is more than a mile. Certainly in some 
trees the root length would much exceed that of Corn. 
The size of a plant’s root system, in general, varies with that of 
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