Plant Tissues and The Vascular System Interest Grabber Let the Water Flow Recall that vascular tissue transports water and nutrients throughout a plant

Plant Tissues and The Vascular System

Interest Grabber•Let the Water Flow

•Recall that vascular tissue transports water and nutrients throughout a plant. Imagine that you and your partner have been asked by a bioengineering firm to design a mechanism that can be used by plants to transport food, water, and essential nutrients to a height of 92 meters.

Section 23-1

1. What plant characteristics must you consider in your design?2. What environmental conditions must you take into account for your

design to be functional? 3. Outline the major characteristics of your design.


Section Outline

• Specialized Tissues in PlantsA. Structure of Seed Plants

1. Roots

2. Stems

3. Leaves

4. Tissue Systems

B. Meristematic Tissue

C. Dermal Tissue

D. Vascular Tissue

1. Xylem

2. Phloem

E. Ground Tissue

Section 23-1


KEY CONCEPT Plants have specialized cells and tissue systems.


Plant tissues are made of three basic cell types.

• Parenchyma cells are the most common plant cell type. – store starch, oils and

water– help heal wounds to

the plant – have thin flexible walls


– they are strong and flexible.– celery strings are strands of collenchyma.– they have unevenly thick cell walls.

• Collenchyma cells provide support to a growing plant.


– second cell wall hardened by lignin– die when they reach maturity – used by humans to make linen and rope

• Sclerenchyma cells are the strongest plant cell type.


Plant organs are made of three tissue systems.

• Dermal tissue covers the outside of a plant. – protects the plant – secretes cuticle of leaves – forms outer bark of trees


– provides support – stores materials in roots and stems – most commonly made of parenchyma

• Ground tissue is found inside a plant.


stem

leaf

root

– two networks of hollow tubes

– xylem transports water and minerals

– phloem transports photosynthetic products

• Vascular tissue transports water, minerals and organic compounds.


Concept Map

include

includes includes includes

includes includes

Section 23-1

Plant Tissues

Dermaltissue

Meristematictissue

Vasculartissue

Groundtissue

Epidermalcells Xylem Phloem Parenchyma

cellsCollenchyma

cellsSchlerenchyma

cells

Tracheids Vesselelements

Sieve tubeelements

Companioncells


Dermal tissue

Vascular tissue

Ground tissue

Stem

Root

Leaf

Section 23-1 Figure 23–1 Root, Stem, and Leaf Tissues


Interest Grabber•Stem Study

•Imagine walking through a botanical garden. You probably would see many different kinds of plants, such as small and large trees, flowering plants, and cacti.

Section 23-3

1. How do the stems of trees, flowering plants, and cacti differ?2. How are the stems of these plants similar?


Section OutlineSection 23-3

StemsA. Stem Structure and Function

B. Monocot and Dicot Stems

1. Monocot Stems

2. Dicot Stems

C. Primary Growth of Stems

D. Secondary Growth of Stems

1. Formation of the Vascular Cambium

2. Formation of Wood

3. Formation of Bark


Comparing Primary and Secondary Growth of StemsComparing Primary and Secondary Growth of Stems

Characteristics

Where It Occurs

Effect on Plant

How It IsProduced

Characteristics

Where It Occurs

Effect on Plant

How It IsProduced

Primary GrowthPrimary Growth Secondary GrowthSecondary Growth

Section 23-3

Compare/Contrast Table

At ends of plants

Increases plant length

By cell division in the apical meristem

In stem

Increases stem width

By cell division in meristems other thanthe apical meristem


Section 23-3

A. Vascular cambium appears

B. Secondarygrowth continues

C. Mature stemdevelops

Epidermis

Cortex

Primaryphloem Vascular

cambiumPrimaryxylem

Pith

Secondaryphloem

Secondary xylem

CorkCorkcambium

Primaryphloem

Secondaryphloem

Secondary xylem

Primaryxylem

Bark

Wood

Figure 23–14 Secondary Growth in Stems


Section 23-3

Wood Bark

Cork

Cork Cambium

Phloem

Vascular Cambium

Xylem: Sapwood

Xylem:Heartwood

Figure 23–15 Layers of a Tree Trunk

Contains old, nonfunctioningxylem that helpssupport the tree

Contains active xylem that transports water and minerals

Produces new xylem and phloem, which increase the width of the stem

Transports sugars produced by photosynthesis

Produces protective layer of cork

Contains old, nonfunctioning phloem that protects the tree


KEY CONCEPT The vascular system allows for the transport of water, minerals, and sugars.


Water and dissolved minerals move through xylem.

• Xylem contains specialized cells. – vessel elements are short and wide– tracheid cells are long and narrow – xylem cells die at maturity

vesselelement

tracheid


– Plants passively transport water through the xylem.– Cohesion is the tendency of water molecules to bond

with each other.

• The cohesion-tension theory explains water movement.

– Adhesion is the tendency of water molecules to bond with other substances.


– absorption occurs at roots

• Water travels from roots to the top of trees.

– cohesion and adhesion in xylem– transpiration at leaves


– water vapor exits leaf stomata– helps pull water to the top

branches

• Transpiration is the loss of water vapor through leaves.


Phloem carries sugars from photosynthesis throughout the plant.

• Phloem contains specialized cells. – sieve tube elements have

holes at ends– companion cells help sieve

tube elements – unlike xylem, phloem tissue is

alive


– plants actively transport sugar from the source– sugar flows to the sink due to pressure differences

sugars

phloem xylem

water

Sugars move from their source, such as photosynthesizing leaves, into the phloem.

1

The sugars move into the sink, such as root or fruit, where the are stored.

3

Water moves from the xylem into the phloem by osmosis, due to the higher concentration of the sugars in the phloem. The water flow helps move sugars through the phloem.

2

• The Pressure-flow model explains sugar movement.

Documents

Plant Tissues and The Vascular System Interest Grabber Let the Water Flow Recall that vascular tissue transports water and nutrients throughout a plant