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March 28, 2005. Plant Tissues. Chapter 26. Jin Hoe Huh. Angiosperms – flowering plants. The angiosperms are seed-bearing vascular plants In terms of distribution and diversity, they are the most successful plants on Earth

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plant tissues

March 28, 2005

Plant Tissues

Chapter 26

Jin Hoe Huh

angiosperms flowering plants
Angiosperms – flowering plants
  • The angiosperms are seed-bearing vascular plants
  • In terms of distribution and diversity, they are the most successful plants on Earth
  • The structure and function of this plant group help explain its success
flowering plant life cycle
Flowering Plant Life Cycle

Diploid

Double fertilization

Meiosis

Meiosis

Haploid

Mitosis without cytoplasmic division

microspores

pollination

Two sperms enter ovule

Female gametophyte

plant life histories
Plant Life Histories
  • Annuals complete life cycle in one growing season
  • Biennials live for two seasons; flowers form in second season
  • Perennials grow and produce seeds year after year
slide5

Shoot and Root Systems

  • Shoot system
  • produces sugars by photosynthesis
  • carries out reproduction

Shoot System

  • Root system
  • anchors the plant
  • penetrates the soil and absorbs water and minerals
  • stores food

Root System

slide6

Shoot and root systems are interdependent

water & minerals

sugar

SHOOT SYSTEM

ROOT SYSTEM

plant tissue systems
Plant Tissue Systems

EPIDERMIS

  • Ground tissue system
  • Vascular tissue system
  • Dermal tissue system

VASCULAR TISSUES

GROUND TISSUES

SHOOT SYSTEM

ROOT SYSTEM

slide8

Meristems – Where Tissues Originate

  • Regions where cell divisions produce plant growth
  • Apical meristems
    • Lengthen stems and roots
    • Responsible for primary growth
  • Lateral meristems
    • Increase width of stems
    • Responsible for secondary growth
apical meristems
Apical Meristems

Lengthen shoots and roots:SAM and RAM

activity at

meristems

Cells that form at apical meristems:

new cells

elongate

and start to

differentiate

into primary

tissues

protoderm epidermis

ground meristem  ground tissues

procambium  primary vascular tissues

lateral meristems
Lateral Meristems

Increases girth of older roots and stems

Cylindrical arrays of cells

vascular cambium secondary vascular tissues

periderm cork cambium

thickening

simple tissues
Simple Tissues

Made up of only one type of cell

Parenchyma

Collenchyma

Sclerenchyma

slide12

Morphology of three simple tissue types

parenchyma

collenchyma

sclerenchyma

parenchyma a simple tissue
Parenchyma: A Simple Tissue
  • Comprises most of a plant’s soft primary growth
  • Cells are pliable, thin walled, many sided
  • Cells remain alive at maturity and retain capacity to divide
  • Mesophyll is a type of parenchyma that contains chloroplasts
collenchyma a simple tissue
Collenchyma: A Simple Tissue
  • Specialized for support for primary tissues
  • Cells are elongated, with walls (especially corners) thickened with pectin
  • Makes stems strong but pliable
  • Cells are alive at maturity
sc l er enchyma a simple tissue
Sclerenchyma: A Simple Tissue
  • Supports mature plant parts
  • Protects many seeds
  • Cells have thick, lignified walls and are dead at maturity
  • Two types:
    • Fibers: Long, tapered cells
    • Sclereids: Stubbier cells
complex tissues
Complex Tissues

Composed of a mix of cell types

Xylem

Phloem

Epidermis

xylem
Xylem
  • Conducts water and dissolved minerals
  • Conducting cells are dead and hollow at maturity

vessel member

tracheids

phloem a complex vascular tissue
Phloem: A Complex Vascular Tissue
  • Transports sugars
  • Main conducting cells are sieve-tube members
  • Companion cells assist in the loading of sugars

sieve plate

sieve-tube

member

companion

cell

epidermis a complex plant tissue
Epidermis: A Complex Plant Tissue

- Covers and protects plant surfaces

- Secretes a waxy, waterproof cuticle

- In plants with secondary growth,periderm replaces epidermis

monocots and dicots same tissues different features
Monocots and Dicots – same tissues, different features

1 cotyledon

2 cotyledons

4 or 5 floral parts

3 floral parts

Netlike veins

Parallel veins

3 pores

1 pore

Vascular bundles dispersed

Vascular bundles in ring

shoot development
Shoot Development

shoot apical

meristem

protoderm

procambrium

ground meristem

cortex

procambrium

pith

primary xylem

primary phloem

bud undeveloped shoot of meristematic tissue
Bud = undeveloped shoot of meristematic tissue

Leaves

Internode

Axillary bud at node

Longitudinal section of terminal bud

internal structure of a dicot stem
Internal Structure of a Dicot Stem

- Outermost layer is epidermis

- Cortex lies beneath epidermis

- Ring of vascular bundles separates the cortex from the pith

- The pith lies in the center of the stem

internal structure of a monocot stem
Internal Structure of a Monocot Stem
  • The vascular bundles are distributed throughout the ground tissue
  • No division of ground tissue into cortex and pith
dicots

Monocots

Dicots

Ground tissue

system

Dermal tissue

system

Dicots and Monocots have different stem and root anatomies

Vascular tissue

system

leaf gross structure
Leaf Gross Structure

DICOT

MONOCOT

petiole

axillary

bud

blade

node

sheath

blade

node

adapted for photosynthesis
Adapted for Photosynthesis
  • Leaves are usually thin
    • High surface area-to-volume ratio
    • Promotes diffusion of carbon dioxide in, oxygen out
  • Leaves are arranged to capture sunlight
    • Are held perpendicular to rays of sun
    • Arrange so they don’t shade one another
leaf structure
Leaf Structure

UPPER

EPIDERMIS

cuticle

PALISADE

MESOPHYLL

xylem

SPONGY

MESOPHYLL

phloem

LOWER

EPIDERMIS

CO2

one stoma

O2

mesophyll photosynthetic tissue
Mesophyll:Photosynthetic Tissue
  • A type of parenchyma tissue
  • Cells have chloroplasts
  • Two layers in dicots
    • Palisade mesophyll
    • Spongy mesophyll
slide31

Collenchyma

Parenchyma

leaf veins vascular bundles
Leaf Veins: Vascular Bundles
  • Xylem and phloem – often strengthened with fibers
  • In dicots, veins are netlike
  • In monocots, they are parallel
root structure
Root Structure
  • Root cap covers tip
  • Apical meristem produces the cap
  • Cell divisions at the apical meristem cause the root to lengthen
  • Farther up, cells differentiate and mature

root apical meristem

root cap

internal structure of a root
Internal Structure of a Root
  • Outermost layer is epidermis
  • Root cortex is beneath the epidermis
  • Endodermis, then pericycle surround the vascular cylinder
  • In some plants, there is a central pith
slide36

epidermis

endodermis

cortex

pericycle

root hair

phloem

xylem

root hairs and lateral roots
Root Hairs and Lateral Roots
  • Both increase the surface area of a root system
  • Root hairs are tiny extensions of epidermal cells
  • Lateral roots arise from the pericycle and must push through the cortex and epidermis to reach the soil

new

lateral

root

secondary growth
Secondary Growth
  • Occurs in perennials
  • A ring of vascular cambium produces secondary xylem and phloem
  • Wood is the accumulation of these secondary tissues, especially xylem
woody stem
Woody Stem

periderm (consists of

cork, cork cambium,

and secondary cortex)

secondary

phloem

HEARTWOOD

SAPWOOD

BARK

vascular cambium

annual rings
Annual Rings
  • Concentric rings of secondary xylem
  • Alternating bands of early and late wood
  • Early wood
    • Xylem cells with large diameter, thin walls
  • Late wood
    • Xylem cells with smaller diameter, thicker walls
types of wood
Types of Wood
  • Hardwood (oak, hickory)
    • Dicot wood
    • Xylem composed of vessels, tracheids, and fibers
  • Softwood (pine, redwood)
    • Gymnosperm wood
    • Xylem composed mostly of tracheids
    • Grows more quickly