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1
Structure of Structure of PlantsPlants
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Primary vs. secondary growth
1. Primary growth – occurs in apical meristems of shoots and roots
• Results in increase in length
2. Secondary growth – derived from secondary or lateral meristems
• Results in increase in girth (width)• Common in trees (wood and bark)
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Roots: (Anchors. Absorbs water & nutrients from soil)
* Two Types1. Taproot = deep into soil2. Fibrous Roots = several branching main
roots
* Root structure- Root Cap the rounded tip containing dead
cells.- Root hairs increase surface absorption area - Xylem transports substances up to the plant- Phloem brings food down to the growing
root
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Tap RootFibrous Roots
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Stems: support the plant and carry substances between the roots and leaves.
* Some stems also store food (starches) like in asparagus.
* They vary in size and shape:- Boabab tree has a huge stems.- Cabbage have short, hidden stems.
Structure of Roots• Root cap covers
the apical meristem at the tip of the root & produces a slimy substance so roots can more easily grow through the ground
• Apical meristem replaces cells of the root cap as they are damaged
Structure of Roots
• Epidermis covers the outside of the root & has extensions called root hairs that absorb water & minerals and increase the surface area of the root
Structure of Stems• Leaves are
attached to stems at nodes & have lateral buds that can develop into new stems or branches
• Internode is space between nodes on a stem
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Leaves: Many different sizes, shapes. (Pine needles, cabbage, oak, etc.)
* Capture sun’s energy for photosynthesis* Structure of a leaf:
- Upper surface cells- Chloroplasts- Veins with xylem and phloem- Underside surface cells- Stomata (“stoma” in Greek means “mouth”,
opening)
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The Structure of a Leaf
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Cuticle
Lower Epidermis
Palisade mesophyll
Vascular Bundle
Spongy mesophyll
Lower Epidermis
Upper Epidermis
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Flower Structure: Not all flowers have same parts. Some have only male parts.
* Sepals = leaf-like structures covering a bud.
* Petals = colorful structures of an open flower.
* Stamens = male parts (stalks topped by knobs)
* Pistils = the female parts in the center of the flower.
- Stigma = sticky tip of the pistil- Style = tube connecting stigma to ovary.
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The Structure of a Flower
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Parts of a Seed EmbryoParts of a Seed Embryo
• Primary root or Radicle• One or two embryonic leaves
called Cotyledons• Plumule becomes the shoot • Stem like portion below
cotyledons called Hypocotyl• Stem like portion above
cotyledons called Epicotyl
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Endosperm (3n)
Seed Coat
CotyledonPlumule
Epicotyl
Hypocotyl
Radicle
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Filament
Anther
Stigma
Style
Ovary
Receptacle
Petal
Sepal Ovule
Flower Structure