Pharmaceutical botany - Lighthouse Survival Blog

20 PHARMACEUTICAL BOTANY
Leaf buds develop leaves.
Flower buds are unexpanded blossoms.
Mixed buds contain both flower and foliage.
As to position buds are either terminal or axillary, either located at
the apex of the stem or branch or in the axils of the leaves. If they
occur on other situations on the stem, or upon roots or leaves they are
termed adventitious buds. If, as often happens, more than one bud
forms in or near the axil of the leaf, it is called an accessory bud.
The Stem
The stem is that part of the plant axis which bears leaves or modi-
fications of leaves and its branches are usually arranged with mathe-
matical regularity.
The functions of a stem are to bear leaves or branches, connect
roots with leaves, and conduct sap.
When the stem rises above ground and is apparent, the plant is
said to be caulescent.
When no stem is visible, but only flower or leaf stalks, the plant is
said to be acaulescent.
Stems vary in size from scarcely one-twenty-fifth of an inch in
length, as in certain mosses, to a remarkable height of 400 ft. upward.
The giant Sequoia of California attains the height of 420 ft.
Direction of Stem Growth.— -Generally the growth of the stem is
erect. Very frequently it may be
Ascending, or rising obliquely upward.
Reclining, or at first erect but afterward bending over and trailing
upon the ground. Ex. : Raspberry.
Procumbent, lying wholly upon the ground.
Decumbent, when the item trails and the apex curves upward.
Ex. :
Vines of the Cucurbitaceas.
Repent, creeping upon the ground and rooting at the nodes, as the
Strawberry.
Stem Elongation.— ^At the tip of the stem there is found a group of
very actively dividing cells (meristem) which is the growing point of
the stem. All the tissues of the stem are deri\-ed from the cells of the
growing point whose activity gives rise in time to three generative
regions which are from without, inward:
(i) Dermatogen, forming epidermis;