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1. STEMS
Professor Joan S. Awingan

2. Functions
1. Support of main body of plant & leaves.
2. Conduct water & food.
3. It helps store water, as in cacti, and the products of
photosynthesis, as in the trunk of sago palm (Metroxylon
sagu) and sweet palm (Arenga pinnata) which store large
stock of starch;
4. Young green stem also performs a minor role in the
production of food through the process of
photosynthesis, but in some species (e.g. cactus) the
stem is the chief photosynthesizing organ.
5. The plant stem serves as a means of asexual reproduction
in many plant species.

3. Parts of a Stem
A node is a point on the stem from which leaves or
buds arise.
The portion between two successive nodes is
the internode.
A bud is an embryonic stem which has the potential
for further plant growth. It may develop into a leaf,
flower, or both.

5. The first stem that develops from a seed arises from
the epicotyl, an embryonic shoot within the seed.

6. CHARACTERISTICS OF HERBACEOUS STEMS
1. Has soft, green stem and naked bud
2. Covered with epidermis
3. Grow to a small diameter
4. Lives only for one season (annual)
5. With primary tissues only
CHARACTERISTICS OF WOODY STEMS
1. Has brown cover and chiefly covered by scales
2. Covered with periderm or bark
3. Grow to a considerable diameter
4. Lives year after year (perennial)
5. With secondary tissues

7. SECONDARY FUNCTIONS OF STEMS
1. Protection – with thorns (hard, straight, pointed structures;
modified branches or stems)
Ex: Rose, Bougainvilla, citrus
2. Photosynthesis – young and green, helps in food production
Ex: Kangkong, Squash
3. Unusual support – with tendrils (thin, leafless, spirally curved
or coiling structures at are sensitive to contact stimuli)
attach the plant to the support
Ex: Squash, Ampalaya, Upo

8. 4. Storage – succulent, can store either water or other
materials
Ex: mucilaginous substances – cactus, sabila
tannins – Acacia tree
resin – coniferous trees
latex – Rubber tree
sugar - sugarcane
5. Reproduction – some plant stems can be used for
vegetative reproduction such as grafting, marcoting,
budding, layering, and marching
Ex: underground stems like
runners – grasses
tubers
rhizomes

17. RHIZOMES - a horizontal underground stem, which grow near
the surface of the soil
Ex: ginger
UNDERGROUND STEMS

18. TUBERS - enlarged ends of special underground branches.
Each tuber has several eyes. Each eye can develop into a
new plant
Ex: potato

19. BULBS - a short disk-shaped underground stem, with many
fleshy scale leaves.
Ex: onion

20. CORM - short, stout, solid and more or less rounded in shape.
It is filled with stored food and grows in a vertical direction.
Ex: gabi

21. STEMS FOR ASEXUAL REPRODUCTION
RUNNER – a slender prostate branch with long or short internodes,
creeping on the ground and rooting at the nodes; is sub-aerial
Ex: strawberry

22. STOLON – a slender lateral branch originating from an
underground stem and growing horizontally outwards. It is like
a runner, however, it is subterranean
Ex: gabi, Bermuda grass

23. OFFSET – like runners, it originates in the axil of a leaf as a short,
more or less thickened horizontal branch. It elongates only to a
certain extent and produces at the apex a tuft of leaves and a
cluster of small roots below
Ex: water hyacinth

24. SUCKER – like the stolon, it is also a lateral branch developing
from the underground part of the stem however, it grows
obliquely upwards and directly gives rise to a leafy shoot or
a new plant
Ex: banana, bamboo

25. TENDRILS – thin, leafless, spirally curved branch by which
climbers attach themselves to other objects
Ex: upo, squash, ampalaya
OTHER SPECIALIZED STEMS

26. THORNS – a modified, hard, straight, sharp-pointed stem. It occurs
in the axil of a leaf where a branch would normally develop.
Ex: lemon, roses, pomelo

27. CLADOPHYLLS – flattened stems and leaf-like in appearance.
It has in its center a node bearing very small scale-like leaves with
axillary buds
Ex: asparagus

28. PHYLLOCLADE – flat, stout and fleshy stems that are modified
For water and food storage. Generally found in plants whose leaves
are very small, may fall off early or modify into spines. Then they
take over the functions of the leaves, particularly photosynthesis
Ex: cactus