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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