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Related article: concealed and unexpanded young flowers.
136 PHARMACEUTICAL BOTANY
3. A mixed bud is a young shoot bearing concealed unexpanded
leaves and flowers.
Classification of Buds According to Position on the Stem. i. A
terminal bud is one which is located on the end of a stem (shoot).
It is capable of elongating into a shoot which bears leaves or both
leaves and flowers.
2. An axillary or lateral -bud is one which arises in the leaf axil.
It is capable of giving rise to a side branch or to a flower. Occa-
sionally axillary buds do not develop and are then called dormant
3. An adventitious bud is Biaxin 500 Mg one which occurs on some position of the
stem other than at its apex or in the axil of a leaf. Such buds may
be seen developing along the veins of a Biaxin 500 Mg Begonia leaf or along the
margin of a Bryophyllum leaf after these have been planted Biaxin 500 Mg in
moist soil for several days.
4. An accessory bud is an extra bud which forms in or near the
Classification of Buds According to Their Arrangement on the Stem.
1. When a single bud is found at each joint or node of a stem, the
buds are said to Biaxin 500 Mg be alternate.
2. When two buds are found at a Biaxin 500 Mg node they are opposite.
3. When several buds occur at a node they are whorled.
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-
Stems usually grow toward the light and so are heliotropic.
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 ^ 5 inch in length, as in certain
mosses, to a remarkable height of 400 feet or more. The giant
Sequoia of California attains the height of 420 feet. Some of the
PLANT ORGANS AND ORGANISMS 137
Eucalyptus trees of Australia and Tasmania are reported to attain
the height of 500 feet.
Nodes and Internodes. The nodes are the joints of stems. They
represent the parts of the stem from which leaves or branches arise.
Internodes are the parts of stems between nodes.
Direction of Stem Growth. Generally the Biaxin 500 Mg growth of the stem is
erect. Very frequently it may be:
Ascending, or rising obliquely upward. Example: Saw Palmetto.
Reclining, or at first erect but afterward bending over and trailing
upon the ground. Example: Raspberry.
Procumbent, lying wholly upon the ground. Example : Pipsissewa.
Decumbent, when the stem trails and the apex curves upward.
Examples: Vines of the Cucurbitacea.
Repent, creeping upon the ground and rooting at the Biaxin 500 Mg nodes, as the
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 derived from the cells of
the growing point whose activity gives rise in time to three genera-
tive regions which are from without, inward:
1. Dermatogen, forming epidermis;
2. Periblem, forming the cortex; and
3. Plerome, forming the fibre-vascular elements and pith.
Duration of Stems.
Annual, the stem of an herb whose life terminates with the season.
Biennial, where the stem dies at the end of the second year.
Perennial, when the stem lives for many years. Example: Oak.
Stem Modifications. (i) twining, by elongation and marked
circumnutation of young internodes as in Convolvulus, Dodder,
etc. (2) Tendriliform by thread-like modification and sensitivity
to contact of a side branch as in Passion flower, Squash, etc. (3)
Spiny, by checking and hardening of a branch that may then become
defensive ecologically as in hawthorn, honey locust, etc. (4)
Aerial tuberous, in which one or more internodes, enlarge above
ground and store reserve food as in pseudobulbs of orchids, Vitis
138 PHARMACEUTICAL BOTANY
gongylodes, etc. (5) Subterranean tuberous in which a subter-
ranean stem or branch enlarges as a food-storing center: (a) annual
type, tuber as in potato, etc., corm as in crocus, etc.; (b) perennial
type, bulbs as in lily (scaly) and onion or hyacinth (tunica ted).
(6) Phylloid or leaf-like in which flattening branch expansion occurs,
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