108 
ORGANOGRAPHY. 
BOOK I. 
Sect. III. Of the Boot, or Descending Axis. 
At or about the same time that the ascending axis seeks 
the light and becomes a stem, does the opposite extremity of 
the seed or bud bury itself in the earth and become a root, 
with a tendency downwards so powerful, that no known force 
is sufficient to overcome it. Correctly speaking, nothing can 
be considered a root except what has such an origin ; for 
those roots which are emitted by the stems of plants are in 
reality the roots of the buds above them, as will be hereafter 
explained. Nevertheless, nothing is more common than even 
for botanists to confound subterranean stems or buds with 
roots, as has been already seen. (See Bulb, Tuber, Soboles, 
&c. &c.) 
Independently of its origin, the root is to be distinguished 
from the stem by many absolute characters. In the first 
place, its ramifications occur irregularly, and not with a sym- 
metrical arrangement: they do not, like branches, proceed 
from certain fixed points (buds), but are produced from all 
and any points of the surface. Secondly, a root has no leaf- 
buds, unless indeed, as is sometimes the case, it has the power 
of forming adventitious ones ; but, in such a case, the irregular 
manner in which they are produced is sufficient evidence of 
their nature. Thirdly, roots have no scales, leaves, or other 
appendages ; neither do they ever indicate upon their surface, 
by means of scars, any trace of such : all underground bodies 
upon which scales have been found are stems, whatever they 
may have been called. A fourth distinction between roots 
and stems is, that the former have never any stomates upon 
their epidermis; and, finally, in Exogens the root has never any 
pith. It has been also said that roots are always colourless, 
while stems are always coloured ; but aerial roots are often 
green, and all underground stems are colourless. 
The body of the root is sometimes called the caudex ; the 
minute subdivisions have been sometimes called radicles, — a 
term that should be confined to the root in the embryo; 
