74 PRACTICAL COURSE IN BOTANY 
the first kind a single stout prolongation called a taproot 
proceeds from the lower end of the hypocotyl and continues 
the axis of growth straight downward, unless turned aside 
by some external influence. A taproot may be either simple, 
nr as in the turnip, radish, and dandelion, 
or branched, as in most shrubs and 
trees. In the latter case the main axis 
is called the primary root, and the 
branches are secondary ones. 
80. Fibrous and fascicled roots. — 
Where the main axis fails to develop, 
as in the corn and grasses generally, 
a number of independent branches take 
its place, forming what are known as 
fibrous roots. Both fibrous and tap- 
Fic. 86.—Branchedtap- YOOts may be either hard or fleshy. 
root of maple. The turnip and carrot are examples of 
fleshy taproots, the dahlia and rhubarb of fascicled roots. 
The function of both is the storage of nourishment. The 
sweet potato is an example of a tuberous root. 
81. Practical importance of this distinction. — The dif- 
ference between axial and fibrous roots has important bear- 
ings in agriculture. The first kind, 
which are characteristic of most dicot- 
yls, strike deep and draw their nour- 
ishment from the lower strata of the 
soil, while the fibrous and fascicled, or 
radial kinds, as we may call them for 
want of a better name, spread out near 
the surface and are more dependent on + 
external conditions. Fic. 87. — Fibrous root. 
82. Roots that grow above ground. — The kinds of 
roots that have just been considered are all subterranean, 
and bring the plant into relation with the earth, whether for 
the purpose of absorbing nourishment, or of mechanical sup- 
port, or, as in the majority of cases, for both. Many plants, 
