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Plant Tissues and the Multicellular Plant Body

Chapter 5 Notes – Pages 90 - 107

White Oak, Illinois State Tree

White oak trees have bark that is off-whitish to ashy gray in color. It can be very scaly and platelike. Older trees often have patches of nearly smooth bark.

Rounded lobes & Acorns

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Read Page 90

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Today, we are going to learn aboutPlant Body Structure Plant Life SpansGround Tissue SystemVascular System TissuesDermal Tissue SystemPlant GrowthPrimary & Secondary growth

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Plant Body StructureAll plants have the same basic body planPlant body is organized into 2 Systems

Root System (underground portion) Tap Root Branch Roots

Shoot System (aerial portion) Stem Leaves Flowers & Fruits *only in flowering plants*

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Plant OrgansRootsStemsLeavesFlower PartsFruits

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Figure 5-1

Branch roots

Developing fruit

Nodes (areas of leaf andaxillary bud attachment)

Axillary bud

Flower

Internode (area betweenadjacent nodes)

Shootsystem

Rootsystem

Rosette ofbasal leaves

Petiole Blade

LeafStem

Taproot

Fig. 5-1, p. 92

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Plants grow below & above groundPlants need resources from both

environmentsBelow ground

Dark Moist Nutrients / Dissolved minerals Roots anchor the plant to the ground Absorbs Water

Above ground Sunlight Carbon Dioxide

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2 Different types of Plant BodyHerbaceous Plants

Do not develop persistent woody parts above ground

Typically green exteriorDie after growing season

Woody Plants Develop persistent woody parts above groundPersist after growing season

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Plant Life SpansAnnuals

Herbaceous plants that grow, reproduce, & die in 1 year or season

Examples: Corn, sunflowers, most food garden plantsBiennials

Herbaceous plants that take 2 years to complete their life cycles

Examples: Carrots, cabbage, celery, & parsleyPerennials

Woody or herbaceous plants that live for more than 2 yearsAerial shoots of herbaceous perennials die each winterGrow back in SpringExamples: All trees, rhubarb, onions, asparagus, iris

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Cells & Tissues of the Plant BodyThe cell is the basic structural and functional

unit of plantsPlant cells are organized into tissuesTissues are groups of cells that form a

structural and functional unitSimple tissues – 1 kind of cellComplex tissues – 2 or more kinds of cells

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3 Plant Tissue SystemsTissues are organized into 3 tissue systems

1. Ground Tissue System Most of the plant body Functions include photosynthesis, storage,

structural support

2. Vascular tissue system (think of veins) The plumbing system of the plant Extends throughout the plant body Conducts water, dissolved minerals, and food

(dissolved sugar)

3. Dermal Tissue System Strengthens & Supports the plant This system covers the plant body (like skin)

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Tissue Systems throughout the plant

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1. Ground System TissueComposed of 3 Simple Tissues

1. Parenchyma Cells have thin primary cell walls Unspecialized – Can differentiate into other

kinds of cells Functions: Photosynthesis, storage, & secretion Most common type of cell & tissue in plants

2. Collenchyma Cells have unevenly thickened primary cell walls

3. Sclerenchyma “Sclero” means “Hard” Cells have both primary cell walls & thick

secondary walls Provides support to plant body

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Parenchyma Cells

Thin Primary Cell Walls

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Collenchyma Cells

Thick Cell Walls

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Sclerenchyma Cells

Have both primary and secondary cell walls

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2. Vascular Tissue SystemComposed of 2 Complex Tissues

Xylem Conducts water and dissolved minerals Transfers from Roots stem & leaves Composed of 2 types of cells

Tracheids – chief water conducting cells Vessel Elements – have holes in end cell walls

Phloem Conducts food throughout the body Composed of 4 types of cells

Sieve-tube elements – highly specialized cells Companion cells Phloem fibers (long tapered cells) Phloem parenchyma cells

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3. Dermal Tissue SystemsComposed of 2 Complex Tissues

EpidermisPeriderm

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EpidermisOutermost layer of herbaceous plant, usually

one cell thickCovers the primary plant body (leaves, young

stems and roots) Prevent Water Loss

Secretes a waxy cuticle Stomata regulates gas exchange using guard

cellsComposed of 2 types of cells

Guard cellsTrichomes

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Stomata

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PeridermReplaces epidermis in woody plantsForms the protective, outer barkOutermost layer of cells covering a woody

stem or root

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Periderm

Geranium

Cortex(interior of stem)

Exteriorenvironment

Remnantsof epidermis

Cork cellsCork cambium P

eri

derm

Corkparenchyma

Fig. 5-10, p. 103

Table 5-2a, p. 104

Table 5-2b, p. 104

Primary GrowthIncrease in stem and root lengthResult of activity of apical meristems at the

tips of roots and at the buds of stems Apical Meristem

An area of cell division at the tip of a stem or root in a plant; produces primary tissues

Bud A dormant embryonic shoot that eventually

develops into an apical meristem

Root Tip

Stem Tip

Secondary GrowthIncrease in stem and root girthSecondary growth is localized, typically as

long cylinders of active growth throughout the lengths of older stems and roots

Lateral MeristemAn area of cell division on the side of a

vascular plantGives rise to secondary tissues2 Lateral Meristems

Vascular Cambium Cork Cambium

Lateral Meristems and Secondary Growth