PLANT STRUCTURE

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PLANT STRUCTURE
EQ How can a plant maintain homeostasis using
its stomata?
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Basic Morphology
Stem
Leaves
3 Organs?
Roots
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Roots?
Anchor
Absorb minerals and water
Store food
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Fibrous root systems
Anchors / Surface Area
No one root is larger than the others
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Taproot system
Anchor / Store Food
One long, thick root with smaller branch roots
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Root hairs
Absorption of water and minerals
Increase the surface area enormously
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Shoots
Stems and Leaves

• Stem Functions
• Hold up leaves to sun
• Transport substances within the plant
• Produce leaves, branches, flowers

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Nodes the points at which leaves are
attached Internodes the stem segments between
nodes Buds where leaves attach to the nodes
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Terminal bud (apex) Growth of a young shoot is
concentrated
Axillary bud
At the angle formed by each leaf and the stem
potential to form a vegetative branch
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Primary Growth growth in length of stem
occurring at the ends of a plant
Secondary Growth growth in the thickness of
stem and root to support the mass of primary
growth
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Leaves
main photosynthetic organs
Blade thin, flattened part, maximize light
absorption
Petiole connects the leaf to a stem node
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Transpiration and Wilting
Transpiration loss of water through leaves.
Helps to cool leaves on hot days but also can
threaten leafs survival if water is limited.
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Anatomy of a Leaf
Cuticle
Blade
Epidermis
Veins
Xylem
Petiole
Palisade mesophyll
Vein
Mesophyll
Phloem
Spongy mesophyll
Gases out O2, H2O Gases in CO2
Chloroplasts
Stoma
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Gas Exchange and Homeostasis
Stomata (singlular stoma) small openings in
the epidermis that allow gases (CO2, O2, H2O) to
diffuse into and out of the leaf.
Guard Cells surround the stomata, control
opening and closing.
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Leaves have become adapted by evolution for other
functions
tendrils to cling to supports
spines for defense
brightly colored for attracting pollinators
modified for water storage