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Vascular Plant Structure & Function

Vascular Plant Structure & Function

There are two major divisions of plants: Vascular plants and nonvascular plants.

Cells of plants (like humans) are organized into a hierarchy: cells, tissues, tissue systems, organs and organ systems.

These structures enables plants to successfully photosynthesize, grow and reproduce.

Photosynthesis

Photosynthesis is the process by which plants synthesize their own carbohydrates

Carbohydrates give energy for:

1. Cell growth

2. Reproduction

3. Provides food for all other animals through food web.

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13.1

shoot tip(terminal bud)

flower

axillary bud

young leaf

node

internode

node

vasculartissues

groundtissues

secondary roots

withered cotyledon

tertiary roots

primary root

Shoot system

Root system

seeds inside fruit

petioleleaf

blade

epidermis

root tips with root caps

young secondary root

germinates, cells at the root and shoot tips divide by mitosis and elongate.Meristems at locations other than the root and shoot tips form complete orincomplete cylinders of tissue within roots and stems. Cell division in these cylin-ders, called the lateral meristems, causes an increase in the diameters of roots and lateral meristems: cylindrical regions in

roots and stems. They are responsible for allincreases in diameters of roots and stems.

Figure 2The two main organ systems of plants arethe root system and the shoot system. Alsoshown are the major tissues, organs, andorgan systems of a typical angiosperm. Notethat not all plants will have all the partsshown, nor will parts with similar functionslook the same from species to species.

Meristems

Meristems: are any region in the plant where cells have the ability to divide by mitosis repeatedly.

Apical Meristems: The meristems located at the tip of the plant root and shoots

Lateral Meristems: cylindrical regions in the roots and stems. They are responsible for all increases in diameter in roots and stems.

Vascular Cambium: a lateral meristem which is responsible for creating new xylem and phloem tissue.

The Meristems

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stems. Cambium (plural: cambia) is another name for a lateral meristem. Celldivision within the vascular cambium produces cells which will become newxylem and phloem tissue.

Primary and Secondary GrowthPrimary growth includes all growth in the length of roots and stems throughouta plant’s entire life and all growth in the diameters of roots and stems whichoccurs in the first year of a plant’s life. Secondary growth is the result of lateralmeristem activity throughout the rest of a plant’s life (Figure 3). Cells producedby meristematic tissue eventually differentiate into all other plant tissues. Thesetissues are arranged into the familiar specialized organs of the plant: roots, stems,leaves, and cones or flowers.

vascular cambium: a lateral meristemwhich is responsible for creating new xylemand phloem tissue

primary growth: all plant growth origi-nating at apical meristems resulting inincreases in length, as well as growth origi-nating at the lateral meristems in the firstyear of a plant’s life

secondary growth: plant growth origi-nating at lateral meristems which results inincreased diameters of roots and stems inthe second and all subsequent years of aplant’s life

shoot apicalmeristems(in buds)

lateralmeristems

shootsystem

root apicalmeristems

rootsystem

Vascular Plant Structure and Function

1. The cells of complex plants are organized into tissues, tissue systems,organs, and organ systems.

2. Primary growth is growth in length and occurs at apical meristems, plus atthe lateral meristems during a plant’s first year.

3. Secondary growth is growth in diameter and occurs at lateral meristems ofplants which live more than one year.

4. Cells produced by meristematic tissue differentiate into all other planttissues.

Figure 3All seed plants have regions of primary(apical and lateral) growth in their first year.If a plant lives more than one year, it con-tinues to have primary apical growth, butafter the first year, it also has secondarygrowth, which is always lateral.

Important note: cells produced in

the meristems will differentiate into

all other plant tissues.

Primary & Secondary Growth

Primary & Secondary Growth

Primary Growth: all plant growthoriginating at apical meristems resulting inincreases in length, as well as growthoriginating at the lateral meristems in the firstyear of plant’s life.

Primary & Secondary Growth

Primary Growth: all plant growthoriginating at apical meristems resulting inincreases in length, as well as growthoriginating at the lateral meristems in the firstyear of plant’s life.

Secondary Growth: plant growth takes placein the rest of the plant’s life. Cells produced bythis meristematic tissue will differentiate intoother plant tissues or plant organs i.e. roots,stems leaves and cones/flowers.

Plant Tissues

PLANT TISSUES

PLANT TISSUESPlant tissues arespecialized for specificfunctions:

PLANT TISSUESPlant tissues arespecialized for specificfunctions:Storage

PLANT TISSUESPlant tissues arespecialized for specificfunctions:

AbsorptionStorage

PLANT TISSUESPlant tissues arespecialized for specificfunctions:

AbsorptionStorage

Photosynthesis

PLANT TISSUESPlant tissues arespecialized for specificfunctions:

AbsorptionStorage

Photosynthesis

Reproduction

PLANT TISSUESPlant tissues arespecialized for specificfunctions:

Absorption

Transport

Storage

Photosynthesis

Reproduction

3 Major Types of Plant Tissue

3 Major Types of Plant Tissue

1. Dermal Tissue: found in the epidermisand periderm.

3 Major Types of Plant Tissue

1. Dermal Tissue: found in the epidermisand periderm.

2. Ground Tissue: all of the internalnonvascular regions of the plant.

3 Major Types of Plant Tissue

1. Dermal Tissue: found in the epidermisand periderm.

2. Ground Tissue: all of the internalnonvascular regions of the plant.

3. Vascular Tissue: specialized forconducting materials throughout the plantbody.

1. DERMAL TISSUE SYSTEMEpidermis: the outermost cell layer of a multicellular plant experiencing primary growth.

Periderm: a protective covering that replaces the epidermis in plants that show extensive secondary growth.

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13.2

Practice

Understanding Concepts1. What four things do plants require for photosynthesis?2. Carbohydrates are produced during photosynthesis. What is supplied

to plants by these carbohydrates and why are they important?3. What are the two basic systems of most plants? 4. Where are apical meristems? What results from their activity?5. What is the difference between primary and secondary growth?6. How would plants that exhibit secondary growth differ in size and

structure from plants that exhibit only primary growth?

13.2 Plant Tissues Plant tissues are specialized for functions such as absorption, transport, storage,photosynthesis, and reproduction. There are three major types of plant tissue—dermal tissue, ground tissue, and vascular tissue—which are distributedthroughout the plant body. Dermal tissue cells are found in the epidermis andthe periderm. Ground tissue cells make up all of the internal nonvascular regionsin the plant. Vascular tissue cells are specialized for conducting materialsthroughout the plant body.

Dermal Tissue SystemThe outermost cell layer of the main plant body is the epidermis. On parts of theshoot system, the epidermis produces on its exterior surface a waxy, noncellularlayer called the cuticle. The cuticle protects against excessive water loss and infec-tion by microorganisms. When you polish an apple, you are polishing this waxycuticle. The cuticle also restricts gaseous exchange through the surfaces of theepidermal cells.

Epidermal tissue often contains highly specialized cells such as root hair cellsand leaf guard cells, which you will learn about later. During secondary growthin roots and stems, the epidermis is replaced by the periderm, another dermaltissue. Some peridermal cells form many layers of special cells that soon die butleave behind a material that waterproofs the roots and stems and protects theinner tissues from structural damage (Figure 1).

epidermis: the outermost cell layer of amulticellular plant experiencing primarygrowth

periderm: a protective covering thatreplaces the epidermis in plants that showextensive secondary growth

Figure 1(a) Epidermal cells cover the outer surfaces

of these Hibiscus leaves. A layer ofcuticle makes these leaves shine.

(b) Epidermal cells of this tree trunk have longago been replaced by periderm cells. Astrees grow laterally through secondarygrowth, the outer material splits, givingdifferent trees their characteristic bark pat-terns. In addition, the bark here is coveredby two kinds of crustose lichen.(a) (b)

Plants: Form and Function 497

13.2

Practice

Understanding Concepts1. What four things do plants require for photosynthesis?2. Carbohydrates are produced during photosynthesis. What is supplied

to plants by these carbohydrates and why are they important?3. What are the two basic systems of most plants? 4. Where are apical meristems? What results from their activity?5. What is the difference between primary and secondary growth?6. How would plants that exhibit secondary growth differ in size and

structure from plants that exhibit only primary growth?

13.2 Plant Tissues Plant tissues are specialized for functions such as absorption, transport, storage,photosynthesis, and reproduction. There are three major types of plant tissue—dermal tissue, ground tissue, and vascular tissue—which are distributedthroughout the plant body. Dermal tissue cells are found in the epidermis andthe periderm. Ground tissue cells make up all of the internal nonvascular regionsin the plant. Vascular tissue cells are specialized for conducting materialsthroughout the plant body.

Dermal Tissue SystemThe outermost cell layer of the main plant body is the epidermis. On parts of theshoot system, the epidermis produces on its exterior surface a waxy, noncellularlayer called the cuticle. The cuticle protects against excessive water loss and infec-tion by microorganisms. When you polish an apple, you are polishing this waxycuticle. The cuticle also restricts gaseous exchange through the surfaces of theepidermal cells.

Epidermal tissue often contains highly specialized cells such as root hair cellsand leaf guard cells, which you will learn about later. During secondary growthin roots and stems, the epidermis is replaced by the periderm, another dermaltissue. Some peridermal cells form many layers of special cells that soon die butleave behind a material that waterproofs the roots and stems and protects theinner tissues from structural damage (Figure 1).

epidermis: the outermost cell layer of amulticellular plant experiencing primarygrowth

periderm: a protective covering thatreplaces the epidermis in plants that showextensive secondary growth

Figure 1(a) Epidermal cells cover the outer surfaces

of these Hibiscus leaves. A layer ofcuticle makes these leaves shine.

(b) Epidermal cells of this tree trunk have longago been replaced by periderm cells. Astrees grow laterally through secondarygrowth, the outer material splits, givingdifferent trees their characteristic bark pat-terns. In addition, the bark here is coveredby two kinds of crustose lichen.(a) (b)

Outer most layer of main plant body is the epidermis

On the shoots epidermis produces a waxy noncellular layer called the cuticle.

Functions of the Cuticle:

1. Protects plant from water loss

2. Protects plant from infection by microorganisms

3. Restricts gas exchange

There are 3 types of ground tissues: parenchyma, collenchyma, and sclerenchyma.

2. GROUND TISSUE SYSTEM

1. PARENCHYMA:

1. PARENCHYMA:

Bulk of the primary plant body

1. PARENCHYMA:

Bulk of the primary plant body

Involved in photosynthesis and storage ofnutrients, carbohydrates and water

1. PARENCHYMA:

Bulk of the primary plant body

Involved in photosynthesis and storage ofnutrients, carbohydrates and water

Involved in healing wounds/regeneratingparts.

1. PARENCHYMA:

Bulk of the primary plant body

Involved in photosynthesis and storage ofnutrients, carbohydrates and water

Involved in healing wounds/regeneratingparts.

Pith: parenchyma tissue at the very centreof roots and stems.

1. PARENCHYMA:

Bulk of the primary plant body

Involved in photosynthesis and storage ofnutrients, carbohydrates and water

Involved in healing wounds/regeneratingparts.

Pith: parenchyma tissue at the very centreof roots and stems.

Cortex: parenchyma tissue that surroundsthe pith made of more rigid cells.

Living cell tissue

Living cell tissue

Plants such as cacti have large amount of parenchyma tissue for water storage are called succulents.

Living cell tissue

Plants such as cacti have large amount of parenchyma tissue for water storage are called succulents.

Example: Cacti

2. Collenchyma: living cell tissues

2. Collenchyma: living cell tissues

helps strengthen the plant and is specialized for supporting the plant’s primary growth regions.

2. Collenchyma: living cell tissues

helps strengthen the plant and is specialized for supporting the plant’s primary growth regions.

These cells are flexible to allow parts to bend

3. Sclerenchyma: cells that are dead atmaturity

3. Sclerenchyma: cells that are dead atmaturity

These cells have thick walls composed ofcellulose and lignin.

3. Sclerenchyma: cells that are dead atmaturity

These cells have thick walls composed ofcellulose and lignin.

material that provides added strength andrigidity to the cell.

3. Sclerenchyma: cells that are dead atmaturity

These cells have thick walls composed ofcellulose and lignin.

material that provides added strength andrigidity to the cell.

Example: shells of nuts, cactus spines.

3. VASCULAR TISSUE SYSTEM

Vascular tissue consists of xylem, phloem, and some collenchyma and parenchyma cells.

3. VASCULAR TISSUE SYSTEM

Vascular tissue consists of xylem, phloem, and some collenchyma and parenchyma cells.

xylem is the main tissue in plants for conducting water and minerals, which is helped by tracheids and vessels. It is made of dead tissue

3. VASCULAR TISSUE SYSTEM

Phloem tissue transports sugars and othersolutes throughout the plant.

Phloem tissue transports sugars and othersolutes throughout the plant.

it is living tissue made of Sieve Tubes:long tubes formed by many sieve elementsto allow easy passage of water anddissolved materials

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