Plants as Living Organisms
Plant Parts and Their Functions
Plant and Soil Science
Topic 2014
Basic Parts of the Plant
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Roots
Stems
Leaves
Flower (not included in this lecture)
Root Functions
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1.
2.
3.
4.
Anchor Plant
Absorb water and minerals
Translocate water and minerals to stem
Store Food
Root Parts
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Primary root
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Secondary root
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First root that the seed sends out
Anchors root
Branches off of primary root
Root Cap
–
Protects roots while they grow
Root Parts
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Root hairs:
Tiny one celled hair like extensions of the epidermal cells
located near the tips of the roots where vascular tissues have
formed.
– Increase surface area
– Absorb water and minerals from soil
Adventitious roots
Roots that begin growth from the stem
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Different type of Roots
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A. Tap Root
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–
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Continuation of the primary root
Ideal for anchorage
Penetration is greater for water
Storage area for food made by photosynthesis
Different type of Roots
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B. Fibrous Roots
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Many finely branched secondary roots
Shallow roots cover a large area
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More effective absorption of water and minerals
Roots hold the soil to prevent erosion
Types of Roots
Stem Function
1. Translocate water, minerals and food to the
leaves
2. Support the leaves and display them to light
3. Store food and water
4. Produces new stem tissue
Stem Tissues
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Xylem
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Provide structural support
Transports water and minerals from roots to leaves
Phloem
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Transports food made in leaves to the rest of the
plant
Buds
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Bud scales
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Terminal Bud
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Primary growing point
Lateral buds
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Tip of twig
Apical Meristem
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Protect under developed parts
Can develop into secondary branches
Apical dominance
–
Hormones that prevent lateral buds from developing
Buds
Leave Function
1. Make food through photosynthesis
2. Provide site of gas exchange
3. Store food
Cross section of Leaf
Principal Tissues of the Leaf
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Epidermis
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Cuticle
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Stomata
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Waxy substance covers the leaves and stems
Waterproof layer that keeps water in plants
Openings in the epidermis mainly located on underside of leaves
Exchange of gases
Guard Cells
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Two cells located on each side of stomata
Open and closes stomata
Principal Tissues of the Leaf
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Mesophyll layer
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Palisade mesophyll
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Spongy mesophyll
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Primary site of photosynthesis
Contains air and chloroplasts
Site of photosynthesis and gas exchange
Veins or vascular bundles
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In spongy mesophyll
Phloem tissues conduct food from photosynthesis to rest of
plant
Xylem tissues conduct water and minerals up to cells in leaves
and stems
Simple vs. Compound
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Simple
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Single leaf blade and a petiole
Compound
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A petiole and more then one leaf blades
Shapes of leaves