Chapter 34: The Plant Body CHAPTER 34 The Plant Body

Chapter 34: The Plant Body

CHAPTER 34The Plant Body


Chapter 34: The Plant BodyVegetative Organs of the Flowering PlantVegetative Organs of the Flowering Plant Body Body

Plant CellsPlant Cells

Plant Tissues and Tissue SystemsPlant Tissues and Tissue Systems

Forming the Plant BodyForming the Plant Body

Leaf Anatomy Supports PhotosynthesisLeaf Anatomy Supports Photosynthesis


Vegetative Organs of the Flowering Plant Body• Monocots typically have a single Monocots typically have a single

cotyledon, narrow leaves with parallel cotyledon, narrow leaves with parallel veins, flower parts in threes or veins, flower parts in threes or multiples of three, and stems with multiples of three, and stems with scattered vascular bundles.scattered vascular bundles.

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Vegetative Organs of the Flowering Plant Body• Eudicots typically have two Eudicots typically have two

cotyledons, broad leaves with netlike cotyledons, broad leaves with netlike veins, flower parts in fours or fives, veins, flower parts in fours or fives, and vascular bundles in a ring. and vascular bundles in a ring.

• Flowering plants that are neither Flowering plants that are neither monocots nor eudicots are generally monocots nor eudicots are generally similar in structure to eudicots. similar in structure to eudicots.

Review Figure 34.1Review Figure 34.1

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Figure 34.1

Figure 34.1Figure 34.1

figure 34-01.jpg


Vegetative Organs of the Flowering Plant Body• The vegetative organs of flowering The vegetative organs of flowering

plants are plants are roots, which form a root roots, which form a root

system, system, stems and stems and leaves, which form a shoot leaves, which form a shoot

system. system.


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Figure 34.2


figure 34-02.jpg


Vegetative Organs of the Flowering Plant Body• Roots anchor the plant and take up Roots anchor the plant and take up

water and minerals.water and minerals.

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Vegetative Organs of the Flowering Plant Body• Stems bear leaves and buds. Stems bear leaves and buds.

Lateral buds form branches. Lateral buds form branches. Apical buds produce cells that Apical buds produce cells that

contribute to stem elongation.contribute to stem elongation.99


Vegetative Organs of the Flowering Plant Body

• Leaves are responsible for most Leaves are responsible for most photosynthesisphotosynthesis

• their flat blades, oriented their flat blades, oriented perpendicular to the sun’s rays, are perpendicular to the sun’s rays, are well adapted. well adapted.


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Figure 34.5


figure 34-05.jpg


Plant Cells

• Plant cell walls have a structure that Plant cell walls have a structure that often corresponds to special functions often corresponds to special functions of the cell. of the cell.

• Walls of individual cells are separated Walls of individual cells are separated by a middle lamella common to two by a middle lamella common to two neighboring cells; each cell has its own neighboring cells; each cell has its own primary wall. primary wall.


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Figure 34.6


figure 34-06.jpg


Plant Cells

• Some cells produce a thick secondary Some cells produce a thick secondary wall. wall.

• Adjacent cells are connected by Adjacent cells are connected by plasmodesmata extending through plasmodesmata extending through both cell walls. both cell walls.

Review Figures 34.7, 34.8Review Figures 34.7, 34.8

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Figure 34.7


figure 34-07.jpg


Figure 34.8


figure 34-08.jpg


Plant Cells

• Parenchyma cells have thin walls. Parenchyma cells have thin walls.

• Many store starch or lipids Many store starch or lipids

• Some others carry out photosynthesis.Some others carry out photosynthesis.

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Plant Cells

• Collenchyma cells provide flexible Collenchyma cells provide flexible support.support.

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Plant Cells

• Sclerenchyma cells provide strength Sclerenchyma cells provide strength and function when dead.and function when dead.

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Plant Cells

• Tracheids and vessel elements are Tracheids and vessel elements are xylem cells that conduct water and xylem cells that conduct water and minerals after the cells die. minerals after the cells die.

Review Figures 34.10Review Figures 34.10

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Figure 34.10


figure 34-10.jpg


Plant Cells

• Sieve tube members are conducting Sieve tube members are conducting cells of the phloem. cells of the phloem.

• Their activities are often controlled by Their activities are often controlled by companion cells. companion cells.


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Figure 34.11


figure 34-11.jpg


Plant Tissues and Tissue Systems• The vascular tissue system conducts The vascular tissue system conducts

water, minerals, and the products of water, minerals, and the products of photosynthesis. photosynthesis.

• The dermal tissue system protects the The dermal tissue system protects the body surface. body surface.

• The ground tissue system produces The ground tissue system produces and stores food materials and and stores food materials and performs other functions. performs other functions.



Figure 34.12


figure 34-12.jpg


Forming the Plant Body

• The apical–basal pattern and the radial The apical–basal pattern and the radial pattern are parts of the plant body pattern are parts of the plant body plan; plan;

• They arise through orderly They arise through orderly development. development.


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Figure 34.13


figure 34-13.jpg



• Plant development differs from Plant development differs from animals. animals.

• The plant body is modular, and the The plant body is modular, and the growth of stems and roots is growth of stems and roots is indeterminate. indeterminate.

• Leaves, flowers, and fruits show Leaves, flowers, and fruits show determinate growth.determinate growth.

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• Meristems are localized regions of cell Meristems are localized regions of cell division.division.

• A hierarchy of meristems generates A hierarchy of meristems generates the plant body.the plant body.

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• Apical meristems at the tips of stems Apical meristems at the tips of stems and roots produce the primary growth and roots produce the primary growth of those organs. of those organs.


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Figure 34.14


figure 34-14.jpg



• Shoot apical and root apical meristems Shoot apical and root apical meristems give rise to primary meristems: give rise to primary meristems: protodermprotoderm ground ground procambium procambium



Figure 34.15


figure 34-15.jpg



• In some plants, the products of In some plants, the products of primary growth constitute the entire primary growth constitute the entire plant body. Others show secondary plant body. Others show secondary growth. growth.

• Two lateral meristems, the vascular Two lateral meristems, the vascular cambium and cork cambium, are cambium and cork cambium, are responsible for secondary growth. responsible for secondary growth.


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• The young root has an apical meristem that The young root has an apical meristem that gives rise to the root cap and three primary gives rise to the root cap and three primary meristems, which produce the three tissue meristems, which produce the three tissue systems. systems. protoderm produces the dermal protoderm produces the dermal

tissue systemtissue system ground meristem produces the ground meristem produces the

ground tissue systemground tissue system procambium produces the vascular procambium produces the vascular

tissue system. tissue system.




• Root tips have three overlapping Root tips have three overlapping zones: zones: the zones of cell division, the zones of cell division, cell elongation, and cell elongation, and cell differentiation.cell differentiation.


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• The dermal tissue system consists of The dermal tissue system consists of the epidermis, part of which forms root the epidermis, part of which forms root hairs responsible for absorbing water hairs responsible for absorbing water and minerals. and minerals.


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Figure 34.16


figure 34-16.jpg



• The ground tissue system of a young The ground tissue system of a young root is the cortex, whose innermost root is the cortex, whose innermost cell layer, the endodermis, controls cell layer, the endodermis, controls access to the stele.access to the stele.

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• The stele, consisting of pericycle, The stele, consisting of pericycle, xylem, and phloem, is the root’s xylem, and phloem, is the root’s vascular tissue system. vascular tissue system.

• Lateral roots arise in the pericycle. Lateral roots arise in the pericycle. • Monocot roots have a central pith Monocot roots have a central pith

region. region.


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Figure 34.17


figure 34-17.jpg



• The shoot apical meristem gives rise to The shoot apical meristem gives rise to three primary meristems, with roles three primary meristems, with roles similar to counterparts in the root. similar to counterparts in the root.

• Leaf primordia on the sides of the Leaf primordia on the sides of the apical meristem develop into leaves.apical meristem develop into leaves.

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• Vascular tissue in young stems is Vascular tissue in young stems is divided into vascular bundles, each divided into vascular bundles, each containing xylem and phloem. containing xylem and phloem.

• Pith occupies the center of the Pith occupies the center of the monocot stem. monocot stem.

• Cortex lies to the outside of vascular Cortex lies to the outside of vascular bundles in monocot, and pith rays lie bundles in monocot, and pith rays lie between them.between them.

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• Many eudicot stems and roots show Many eudicot stems and roots show secondary growth, in which vascular secondary growth, in which vascular and cork cambia give rise to secondary and cork cambia give rise to secondary xylem and phloem. xylem and phloem.

• As secondary growth continues, wood As secondary growth continues, wood and bark are produced. and bark are produced.


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Figure 34.19 – Part 1

Figure 34.19 – Part 1Figure 34.19 – Part 1

figure 34-19a.jpg


Figure 34.19 – Part 2

Figure 34.19 – Part 2Figure 34.19 – Part 2

figure 34-19b.jpg



• The vascular cambium lays down The vascular cambium lays down layers of secondary xylem and layers of secondary xylem and phloem. phloem.

• Living cells within these tissues are Living cells within these tissues are nourished by vascular rays.nourished by vascular rays.

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• The periderm consists of cork, cork The periderm consists of cork, cork cambium, and phelloderm, all pierced cambium, and phelloderm, all pierced at intervals by lenticels that allow gas at intervals by lenticels that allow gas exchange.exchange.

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Leaf Anatomy Supports Photosynthesis• Mesophyll is the photosynthetic tissue Mesophyll is the photosynthetic tissue

of a leaf. of a leaf.

• Veins bring water and minerals to the Veins bring water and minerals to the mesophyll and carry products of mesophyll and carry products of photosynthesis to other parts of the photosynthesis to other parts of the plant body.plant body.

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Leaf Anatomy Supports Photosynthesis • A waxy cuticle prevents water loss A waxy cuticle prevents water loss

from the leaf, but is impermeable to from the leaf, but is impermeable to carbon dioxide. carbon dioxide.

• Guard cells control opening of Guard cells control opening of stomata, leaf openings that allow COstomata, leaf openings that allow CO22 to enter but also water to escape. to enter but also water to escape.


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Figure 34.23


figure 34-23.jpg

Documents

Chapter 34: The Plant Body CHAPTER 34 The Plant Body