Pharmaceutical botany - Lighthouse Survival Blog

1 PHARMACEUTICAL BOTANY
DIFFERENCES BETWEEN ROOT AND STEM
The Root The Stem
L. Descending axis of plant. i. Ascending axis of plant.
2. Growing point sub-apical. a. Growing px)int apical.
3. Contains no chlorophyll. 3. Chlorophyll sometimes present.
4. Branches arranged irregularly. 4. Branches with mathematical regularity.
5. Does not bear leaves or leaf rudi- 5. Bears leaves and modifications.
ments.
6. Structure comparatively simple. 6. Structure better defined.
Classification of Roots as to Form.—^i .
Primary or first root, a
direct downward growth from the seed, which, if greatly in excess of the
lateral roots, is called the main or tap root. Ex. : Taraxacum,
Radish.
2. Secondary roots are produced by the later growths of the stem,
such as are covered with soil and supplied with moisture. Both primary
and secondary roots may be either fibrous or fleshy.
The grasses are good examples of plants having fibrous roots.
Fleshy roots may be multiple, as those of the Dahlia, or may assume
simple forms, as follows:
Fusiform, or spindle-shaped, like that of the radish or parsnip.
Napiform or turnip-shaped, somewhat globular and becoming ab-
ruptly slender then terminating in a conical tap root, as the roots of
the turnip.
Conical, having the largest diameter at the base then tapering, as
in the Maple.
3. Anomalous roots are of irregular or unusual habits, subserving
other purposes than the normal.
4. Adventitious roots are such as occur in abnormal places on
developing on Bryophyllum leaves.
the plant. Ex. : Roots
5. Epiphytic roots, the roots of epiphytes, common to tropica]
forests, for example, never reach the soil at all, but cling to the bark
of trees and absorb nutriment from the air. Ex. : Roots of Vanilla.
6. The roots of parasitic plants are known as haustoria. These
penetrate the bark of plants upon which they find lodgment, known
as hosts, and absorb nutritious juices from them. The Mistletoe,
Dodder and Geradia are typical parasites.
Duration of Root.— 'Plants are classified according to the duration
of the root, as follows:
I Annual .
plants are herbs with roots containing no nourishment
for future use. They complete their growth, producing flower, fruit and
seed in a single season, then die.