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Unit #5 ~ We are almost done!
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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