Transcript The Structure of Flowering Plants

The Structure of
Flowering Plants
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Contents
External Structure
The Root System
- Functions
The Shoot System
- Buds
- Leaves
- Flowers
Growth and Tissues in
plants
Organisation of plant
tissues
Types of tissues
Vascular Tissues in
Angiosperms
Xylem
Phloem
Sieve tube cells
Companion cells
Monocot & Dicot plants
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External
Structure
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The Root System
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Roots

Usually white in colour – why?

Tip protected by root cap

Root hairs – absorb water and minerals
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Functions of the root
1.
To anchor the plant in the ground
2.
To absorb water and minerals from the
soil
3.
Sometimes to store food
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The Shoot System
Consists of an upright stem bearing

Buds

Leaves

Flowers
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Functions of the stem
1.
2.
3.
4.
Transport water and minerals from the
roots to all parts of the plant
Transport food from the leaves to all
parts of the plant
Support the leaves and hold them up
to the sun for light
Sometimes to store food
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Buds
(1/2)

A bud is an undeveloped shoot

Apical buds – at tip of stem where
growth takes place

Lateral buds – in axil of leaf – produce
side shoots and branches
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Buds
(2/2)

Axil = angle between the petiole of a
leaf and the stem

Node = point on a stem where a leaf or
leaves are attached

Internode = the part of a stem between
two nodes
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Leaves


Lamina = flattened leaf blade
Veination of leaf – two types
1. Netted e.g.
2. Parallel e.g.

Attachment to stem – two ways
1. Petiole e.g.
2. Sessile e.g.
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Functions of the leaf
1.
To make food by photosynthesis
2.
To allow exchange of gases – explain
3.
To allow transpiration – explain
4.
Sometimes to store food e.g.
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Flowers
Formed from flower buds
 May occur singly or as an inflorescence
Four main parts
 Sepals
 Petals
 Stamens
 Carpels

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Typical flower structure
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Function of the Flower
1.
Reproduction
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Growth and Tissues in plants
meristem: tip of shoots and roots of
plants. Area of active cell division
(mitosis) which produces ‘simple’ cells
which later undergo elongation and
differentiation to give rise to the various
plant tissues e.g. xylem, phloem, etc.
Apical meristems are found at tip of
shoots and roots
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Organisation of plant tissues
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Types of tissues
When meristems divide they produce
three types of tissue
1. Dermal – epidermis = outer covering
2. Ground – inside of plant
e.g. cortex and pith of stem
mesophyll of leaf
3.
Vascular – transport tissue = xylem &
phloem
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Tissue types in L.S. of root
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Tissue types in T.S. of root
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Tissue types in L.S. of stem
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Tissue types in T.S. of stem
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Tissue types in T.S. (V.S.) of leaf
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Vascular Tissues in Angiosperms
Two types
 Xylem
– provides support and
– transports water and minerals

Phloem
– transports food
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Xylem

Two kinds of conducting cell
– xylem tracheids and
– xylem vessels

On maturity both are dead, hollow and
contain no cytoplasm
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Xylem tissue
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Xylem tracheids

Long cells tapered at both ends

Pits in the walls – allow water and
minerals to move sideways from cell to
cell

Walls thickened with lignin for support
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Xylem vessels

Elongated cells with spiral bands of
lignin

No end walls – form a continuous tube

Wider than tracheids
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Phloem

Consists of
– phloem sieve tube cells and
– companion cells
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T.S. of phloem tissue
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L.S. of phloem tissue
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Sieve tube cells

Long cylindrical cells stacked end to
end

End walls = sieve plates – have holes

Allow cytoplasm to move from cell to
cell

Mature cells have no nucleus
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Companion cells

Found beside sieve tube cells

Has cytoplasmic connections with sieve
tube cell

Has a nucleus which controls activities
of both companion and sieve tube cell
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Identification of Monocot &
Dicot plants
Monocotyledons
Number of
cotyledons
One
Arrangement of Scattered in the stem
vascular
bundles in the
stem
Dicotyledons
Two
In a distinct ring pattern
Leaf venation
Parallel
Netted
Number of
flower parts
In threes
In fours and fives
Woody or
herbaceous
Almost all are
May be woody or
herbaceous, there are herbaceous
very few woody
monocotyledons
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The differences between
monocots and dicots
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END
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