BI 103: Plant-Animal A&P Moncots vs Dicots Rootscf.linnbenton.edu/mathsci/bio/bienekr/upload/BI...
Transcript of BI 103: Plant-Animal A&P Moncots vs Dicots Rootscf.linnbenton.edu/mathsci/bio/bienekr/upload/BI...
4/24/2014
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BI 103: Plant-Animal
A&P
Lec 3
• Moncots vs Dicots
• Roots
Learning Objectives
What is the function of the plant root?
How are specific cells and tissues adapted
in the root in order to help it function?
How are tissues in the root different from
the leaves & stem?
How does the root filter water?
What are examples of specialized roots?
Describe mutualisms plant roots may have
with fungi & bacteria.
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Angiosperms, the
flowering plants fall
under two groups:
Monocots or Dicots
Plant Anatomy: Vegetative Organs
Leaves:
Roots:
Stem:
Form = Function
Photosynthesis
Gas exchange
Light absorption
Anchorage
Storage
Transport
Absorption
Support
Transport
Storage
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External Anatomy
of a Root
Root Cap -protects the apical meristem as the root pushes through the soil.
Root Hairs - increase the surface area of the root.
root hair epidermis
cortex
endodermis
of cortex
pericycle
xylem
phloem
apical
meristem
vascular
cylinder
root
cap
Internal Anatomy
Fig. 43-13
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Functions of Roots
Roots 1) Anchor the plant
2) Absorb & filter water
3) Absorb minerals
4) Store surplus sugars
5) Transport water, minerals and sugars and hormones
6) Produce some hormones
7) Interact with soil fungi and bacteria
DICOT MONOCOT
Organs: ROOT
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Organ: Root
1. Epidermal
Epidermis
Endodermis
Root hairs
2. Meristematic
Pericycle
3. Ground
Parenchyma
4. Vascular
Xylem
Phloem
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Organ: Root
1. Epidermal
Epidermis
Endodermis
Root hairs
2. Meristematic
Pericycle
3. Ground
Parenchyma
4. Vascular
Xylem
Phloem
1. Epidermal tissue in roots
A. Epidermis
Lacks waxy cuticle
B. Root hairs
Increase surface area for absorption
C. Endodermis
Contains casparian strip made of
suberin
Filters water
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Dermal tissue in roots
Mineral and Water Uptake by Roots vascular cylinder
xylem
pericycle endodermis
endodermal
cells
Casparian strip
cell walls
soil particles
water
root
hair
air
plasmodesmata
cortex epidermis
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2
3
4
5
(a) Pathways of mineral and water uptake
(b) Endodermal cells, showing the Casparian strip
Fig. 43-17
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Organ: Root
1. Dermal
Epidermis
Endodermis
Root hairs
2. Meristematic
Pericycle
3. Ground
Parenchyma
4. Vascular
Xylem
Phloem
2. Meristematic
Lateral root formation
– Continues to divide, even
after mature
– Forms lateral (branch)
roots and part of the
vascular cambium
A. Pericycle
- Outer boundary of vascular cylinder
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Organ: Root
1. Epidermal
Epidermis
Endodermis
Root hairs
2. Meristematic
Pericycle
3. Ground: “Cortex”
Parenchyma
4. Vascular
Xylem
Phloem
3. Ground tissue
A. Cortex--Region of
ground tissue
B. Made up of
parenchyma cells
between epidermis
and vascular cylinder
Functions: Mostly stores
food
In the form of starch
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Organ: Root
1. Epidermal
Epidermis
Endodermis
Root hairs
2. Meristematic
Pericycle
3. Ground: “Cortex”
Parenchyma
4. Vascular
Xylem
Phloem
Root Types
Tap
Fibrous
Adventitious
- prop
- butressed
- aerial
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Taproots and Fibrous Roots Fig. 43-12
Prop Roots
Example:
Corn - Prop roots support
plants in high wind
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Buttress Roots
Stability in shallow soil
--Tropical Trees
Aerial Roots
Orchids -
Velamen roots,
with epidermis
several layers
thick to reduce
water loss
Ivies (English
ivy, Virginia
creeper) - Aerial
roots aid plants
in climbing
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Specialized roots
Contractile Roots
Pull plant deeper into the soil
Example: Trillium ovatum (Family: Liliaceae)
Specialized roots: Haustoria
Cusucuta spp.
Aka ‘Dodder’
Parasitic roots
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Specialized Roots
Pneumatophores
In plants with roots
growing in water
Spongy roots that
extend above the
water’s surface
Enhance gas
exchange between
atmosphere and
subsurface roots
Mangrove pneumatophores
Mycorrhizae: A Root–Fungus
Symbiosis
Fig. 43-19
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1. Endomycorrhizal fungi
Internal fungal associations
Also known as: vasicular-arbuscular
1. Endomycorrhizal fungi
Internal
fungal
associations
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2. Ectomycorrhizal fungi
External fungal associations
2. Ectomycorrhizal fungi
External fungal
associations
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Root Nodules House
Nitrogen-Fixing Bacteria nitrogen-fixing bacteria within
cortex cells of nodules
epidermis
nodule
Fig. 43-20