4/3/2014

BI 103: Laboratory 1

Plant tissues & morphology

Tissues & Organs I. Plants have three -four major groups of organs: 1. Roots 2. Stems 3. Leaves 4. Flowers

II. Each organ is composed of tissues.  A tissue is a group of cells performing a similar function.

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Plant Anatomy: Vegetative Organs

Leaves: Stem: Arise from stem Place leaves, buds, & roots attach

Roots: Arise from stem

Plant Anatomy: Vegetative Organs

Leaves: Stem: Photosynthesis Support Gas exchange Transport Light absorption Storage

Roots: Anchorage Storage Form = Function Transport Absorption

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Kale Broccoli

Wild Brassica oleracea

Cauliflower

Cabbage

Kohlrabi

Brussels sprouts

Plant Organs: human cultivation and manipulation

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Plant Anatomy: Tissues

4 Tissues: 1. Meristematic 2. Ground 3. Vascular 4. Dermal

Plant Growth

Meristems – Tissues of plants that add new growth. Regions of actively dividing cells.

Apical – increases length/height (primary) Lateral – increases girth. (secondary)

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Plant Anatomy: Tissues and Cells Meristematic Tissue

Apical Pericycle Vascular Cork Meristem Cambium Cambium Functions of Meristematic Tissue: • Growth • Primary (length) • Secondary (girth)

Apical Growth  Root: pericycle  Shoot: Apical meristem

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Apical Meristem

Aka lateral buds

Leaf Apical Primordia Meristem

Older Leaf Primordia Axillary Bud (developing) Primordia

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Old Tjikko– can trees live forever?

 9,550 yrs old root system  Norway spruce in Sweden  Trunk itself only ~700 yrs old

Secondary Growth

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Types of Tissues

 Dermal tissue system – protects plant

 Ground tissue system –

 Vascular tissue –

Tissues and Cells Epidermal Tissue

Epidermis Guard Trichomes Root hairs Cells

Functions of Dermal Tissue: • Protection • Regulates movement of materials

Trichomes:

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Dermal Tissues I. Cuticle – waxy coating II. Epidermis – for outer layer III. Trichomes – Hairs for preventing water loss. IV. Periderm – outer bark V. Guard cells & Stomata

Guard Cells

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Types of Tissues  Dermal tissue system – protects plant

 Ground tissue system – Provides support, stores starch, and carries out photosynthesis.

 Vascular tissue –

Tissues and Cells Ground Tissue

Parenchyma Collenchyma Sclerenchyma Flexible Rigid Large cell Small Cell Thin cell wall Thickest cell wall

Functions of Ground Tissue: • Support: water filled vacuoles • Storage: starch • Photosynthesis

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Ground tissue

Parenchyma cells: • Majority of cells in the plant. • Thin, pliable walls • Large vacuoles and various secretions Parenchyma cells • These cells photosynthesize in leaves. • Living

Tissues and Cells: Ground Tissue

In Roots: Parenchyma Parenchyma contain extra In Leaf: starch in the In Stem: Mesophyll cells cortex for storage Parenchyma form Contain lots of pith for support chloroplasts for photosynthesis

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Ground tissue

Collenchyma cells:

• Cell walls moderately thick • Flexible support Collenchyma cells • Living cells

Ground tissue

Sclerenchyma tissue - • Thick, tough, secondary walls, normally impregnated with lignin Sclereids • Function in support • Dead at maturity Two types: • Sclereids - Stone Cells • Fibers- long and thin

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Sclereids

Fibers:

• Sclereids - Stone Cells • Fibers- long and thin

Types of Tissues  Dermal tissue system – protects plant

 Ground tissue system – Provides support, stores starch, and carries out photosynthesis.

 Vascular tissue – Conducts fluids and helps strengthen roots, stems and leaves.

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Tissues and Cells Vascular Tissue

Tracheids Vessel Sieve Tube Companion Elements Members Cells

Xylem Phloem Functions of Vascular Tissue: • Transport • Support

Vascular Tissue I. Xylem – water & minerals conducting pipes. --Wood is mostly xylem, -- dead at maturity II. Phloem – transports sugars & hormones -- Sap runs through phloem

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Complex plant conducting tissues > xylem >phloem a young corn stem is shown here.

Secondary Growth

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