Download Lec 2: Plant tissues

4/3/2014
BI 103: Laboratory 1
Plant tissues
& morphology
Tissues & Organs
I. Plants have three -four
major groups of organs:
1. Roots
2. Stems
3. Leaves
4. Flowers
II. Each organ is
composed of tissues.
 A tissue is a group of
cells performing a
similar function.
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Plant Anatomy: Vegetative Organs
Leaves:
Arise from stem
Stem:
Place leaves, buds,
& roots attach
Roots:
Arise from stem
Plant Anatomy: Vegetative Organs
Leaves:
Photosynthesis
Gas exchange
Light absorption
Stem:
Support
Transport
Storage
Roots:
Anchorage
Storage
Transport
Absorption
Form = Function
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Broccoli
Kale
Wild Brassica oleracea
Cauliflower
Cabbage
Kohlrabi
Brussels
sprouts
Plant Organs: human cultivation and manipulation
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Plant Anatomy: Tissues
4 Tissues:
1. Meristematic
2. Ground
3. Vascular
4. Dermal
Plant Growth
Meristems – Tissues of plants that add
new growth. Regions of actively
dividing cells.
Apical – increases length/height (primary)
Lateral – increases girth. (secondary)
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Plant Anatomy: Tissues and Cells
Meristematic
Tissue
Apical Pericycle Vascular
Cork
Meristem
Cambium
Cambium
Functions of Meristematic Tissue:
• Growth
• Primary (length)
• Secondary (girth)
Apical Growth
 Root: pericycle
 Shoot: Apical
meristem
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Apical Meristem
Aka lateral buds
Leaf
Primordia
Older Leaf Primordia
(developing)
Apical
Meristem
Axillary Bud
Primordia
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Old Tjikko– can trees live
forever?
 9,550 yrs old root
system
 Norway spruce in
Sweden
 Trunk itself only
~700 yrs old
Secondary Growth
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Types of Tissues
 Dermal tissue system – protects plant
 Ground tissue system –
 Vascular tissue –
Tissues and Cells
Epidermal
Tissue
Epidermis Guard
Cells
Trichomes
Root hairs
Functions of Dermal Tissue:
• Protection
• Regulates movement of materials
Trichomes:
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Dermal Tissues
I.
II.
III.
IV.
V.
Cuticle – waxy coating
Epidermis – for outer layer
Trichomes – Hairs for preventing water loss.
Periderm – outer bark
Guard cells & Stomata
Guard Cells
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Types of Tissues
 Dermal tissue system – protects plant
 Ground tissue system – Provides
support, stores starch, and carries out
photosynthesis.
 Vascular tissue –
Tissues and Cells
Ground
Tissue
Parenchyma
Flexible
Large cell
Thin cell wall
Collenchyma Sclerenchyma
Rigid
Small Cell
Thickest cell wall
Functions of Ground Tissue:
• Support: water filled vacuoles
• Storage: starch
• Photosynthesis
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Ground tissue
Parenchyma cells:
• Majority of cells in the
plant.
• Thin, pliable walls
• Large vacuoles and
various secretions
Parenchyma cells
• These cells
photosynthesize in leaves.
• Living
Tissues and Cells: Ground Tissue
Parenchyma
In Leaf:
Mesophyll cells
Contain lots of
chloroplasts for
photosynthesis
In Stem:
Parenchyma form
pith for support
In Roots:
Parenchyma
contain extra
starch in the
cortex for storage
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Ground tissue
Collenchyma cells:
• Cell walls moderately
thick
• Flexible support
• Living cells
Collenchyma cells
Ground tissue
Sclerenchyma tissue • Thick, tough, secondary walls,
normally impregnated with
lignin
• Function in support
• Dead at maturity
Two types:
• Sclereids - Stone Cells
• Fibers- long and thin
Sclereids
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Sclereids
Fibers:
• Sclereids - Stone
Cells
• Fibers- long and thin
Types of Tissues
 Dermal tissue system – protects plant
 Ground tissue system – Provides
support, stores starch, and carries out
photosynthesis.
 Vascular tissue – Conducts fluids and
helps strengthen roots, stems and
leaves.
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Tissues and Cells
Vascular
Tissue
Tracheids
Xylem
Vessel Sieve Tube Companion
Elements Members
Cells
Phloem
Functions of Vascular Tissue:
• Transport
• Support
Vascular Tissue
I. Xylem – water &
minerals conducting
pipes.
--Wood is mostly
xylem,
-- dead at maturity
II. Phloem – transports
sugars & hormones
-- Sap runs through
phloem
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Complex plant
conducting tissues
> xylem
>phloem
a young corn stem is
shown here.
Secondary Growth
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