UNIT – I
Plant Morphology
Morphology is the name given to the science that study of the structure on
plant parts is called Plant Morphology
Flowering Plants:
1) Root
2) Stem
3) Leaf
4) Flowers
5) Fruit
6) Seed
Flowering Plants :
Flowering plants are the most diverse group of land plants with 300,000
known species.
These are also known as angiosperms and produce seed-bearing fruits.
It is believed that the flowering plant evolved from gymnosperms during the
Triassic period and the first flowering plant emerged 140 million years ago.
Flowers are the reproductive organs of the flowering plants and the most
important feature that distinguishes them from other seed plants.
The flowering plants reproduce by the process of pollination.
In this, the pollen grains transfer from the anther of the male flowers to the
stigma of the female flower where fertilization occurs and seed is formed.
Root System:
The root is a brown, nongreen and underground part of a plant. Root with
their branches is collectively called a root system. There are three types of
the root system:
Taproot System:
The taproot is mainly found in dicotyledonous plants. It develops from the
radicle of the germinating seed, along with its primary roots and branches,
giving rise to the taproot system. Mustard seeds, mangoes, grams and
banyan are a few examples of dicotyledonous plants with taproot system.
Fibrous root System:
The fibrous root is mainly found in ferns and in all monocotyledonous plants.
This root develops from thin, moderately branching roots or primary roots,
growing from the stem.
1 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, The fibrous root system usually does not penetrate deep into the soil,
therefore, on full maturity, these roots look like a mat or a carpet on the
floor. Wheat, paddy, grass, carrots, onion, grass are a few examples
of monocotyledonous plants with the fibrous root system.
The Adventitious root System:
The roots which originate from any part of the plant body other than the
radicle is called the adventitious root system.
This root system is mainly found in all monocotyledonous plants. In plants,
the adventitious root system is used for various purposes, like mechanical
support, vegetative propagation, etc.
Banyan tree, maize, oak trees, horsetails are a few examples
of monocotyledonous plants with the adventitious root system.
Stem:
The stem is the part of the plant which is found above the ground. The bark
of trees are brown in colour and younger stems are green in colour.
It forms the basis of the shoot system and bears leaves, fruits and flowers.
The region where the leaves arise is known as the node and the region
between the nodes is known as the internode.
The trunk is covered by a thick outer covering known as the bark. Overall
stem provides a definite framework and structure to a plant, which later
develops into a tree.
The stem provides support to the plant. They also protect the plant and help
in vegetative propagation. A few underground stems such as potato and
ginger are modified to store food.
The important functions of a stem include:
A stem carries out a number of functions essential for various processes such
as photosynthesis.
Provides a definite framework and structure to a plant which later develops
into a tree.
Support Primary function of the stem is to hold up buds, flowers, leaves, and
fruits to the plant.
Transportation It is the part which transports water and minerals from the
root and prepared food from leaves to other parts of the plant.
Storage Stems are one of the storerooms of plants where the prepared food
is stored in the form of starch. The stems of a few plants in the desert areas,
such as Opuntia, get modified into thick, fleshy structures that store food and
prevent excessive water loss due to transpiration.
Reproduction A few stems help in reproduction through vegetative
propagation and also help to bear flowers and to produce fruits.
The stems of a few plants in the desert areas, such as Opuntia, get modified
into thick, fleshy structures that store food and prevent excessive water loss
due to transpiration.
Leaves:
Leaves are the most important part of a plant. They contain chlorophyll that
helps the plants to prepare their food using sunlight, carbon dioxide and
water.
A leaf consists of three main parts- petiole, leaf base and lamina.
The petiole keeps the leaf blade exposed to wind and cools the leaf.
The leaf base is a protruding part of a leaf.
The lamina of the leaf contains veins and veinlets that provide rigidity to the
leaf blade and help in the transport of mineral nutrients.
2 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, Primarily, leaves have three main functions:
Photosynthesis: Green leaves prepare food for plants by using water and
carbon dioxide in the presence of sunlight. This process is called
photosynthesis.
Transpiration: Other than photosynthesis, leaves play a crucial role in the
removal of excess of water from plants through tiny pores called stomata.
This is the process of transpiration.
Reproduction: Leaves of some plants helps in reproduction also. For e.g.
leaves of Bryophyllum give rise to a new Bryophyllum plant.
Leaf and its parts
Flowers:
Flowers are the most beautiful and colourful part of a plant. They are the
reproductive part of a plant. A flower has four major parts, namely,
Petals: It is the colourful part of a flower which attracts insects and birds.
Sepals: Sepals are green leafy parts present under petals and protect the
flower buds from damage.
Stamens: This is the male part of the flower consisting of anther and
filament.
Pistil: This is the female part of the flower consisting of stigma, style and
ovary.
Fruits:
Fruits are the main features of a flowering plant.
It is a matured ovary that develops after fertilisation.
Some fruits are developed without fertilization and are known
as parthenocarpic fruits and the process is known as Parthenocarpy.
Types of Fruits:
There are three different types of fruits and are classified mainly based on
their mode of development.
Simple- Developed from the monocarpellary ovary or multicarpellary
syncarpous ovary. Examples of simple fruits.
Aggregate–Developed from the multicarpellary apocarpous ovary. Examples
of aggregate fruits.
Composite–These are false fruits, developed from the entire inflorescence
rather than from single flower. Examples of composite fruits include
blackberries, Raspberries strawberries, etc.
Seed:
A seed is a basic part of a plant, which is found enclosed within the fruit. It is
made up of a seed coat and an embryo.
During the development of the fruit, the wall of the ovary becomes the
pericarp.
In some plants, the ovary wall dries out completely, while in some it remains
fleshy.
3 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, Types of Seeds:
Monocot: The seeds of these plants cannot be divided into two equal halves.
Dicot: The seeds of these plants can be divided into two equal halves.
Based on the number of cotyledons, seeds are further classified into two
types- dicotyledonous and monocotyledonous seeds.
Monocotyledonous— The embryo consists of an embryo axis and has only
one cotyledon.
The monocotyledonous is also known as monocot seeds. Grains including
rice, millet, wheat and other plants like onions, corn, ginger banana, palm
tree, are examples of monocot seeds.
Dicotyledonous— The embryo consists of an embryo axis and has two
cotyledons.
The dicotyledons are also known as dicots or dicot seeds. Legumes including
beans, lentils, pea, peanuts, and tomato are examples of dicot seeds.
ROOT SYSTEM :
Roots are the non-leafy part of a plant’s body that grow below the soil.
They support the plant body and help to anchor the plant to the ground.
The roots also help in the absorption of nutrients from the soil.
We also see several types of modified roots, like floating roots and aerial
roots.
Root is the descending or underground part of the plant axis.
Root is usually positively geotropic (i.e. grows downward into the soil) and
positively hydrotropic (i.e. grows towards the source of water) but negatively
phototropic
(i.e. grows away from sunlight).
Root is usually cylindrical and non-green (i.e. lack chlorophylls), but
sometimes green as in Trapa and Taeniophylum.
Root does not bear nodes, internodes, leaves or buds (exceptions are sweet
potato, wood apple etc.)
The growing point of root tip is sub-terminal and protected by a root cap or
calyptra.
Unicellular root hairs present just behind the root caps which increase the
absorptive surface area of roots,
Lateral roots are endogenous in origin i.e. arise from pericycle of the main
root.
Parts of a Root System:
The root system consists of the primary root and all its parts.
Types of Roots:
It is the primary root.
It persists throughout the lifetime of a plant.
Found in dicot plants.
This type of root grows very deep into the soil. Example: Carrot and
beetroot.
Primary Root:
It is the main trunk of the root system that grows underneath the soil layer.
All other parts of the root system emerge from the primary root.
Lateral Root:
These roots emerge horizontally from the primary root.
They grow and form the branching pattern of the root system.
4 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
Plant Morphology
Morphology is the name given to the science that study of the structure on
plant parts is called Plant Morphology
Flowering Plants:
1) Root
2) Stem
3) Leaf
4) Flowers
5) Fruit
6) Seed
Flowering Plants :
Flowering plants are the most diverse group of land plants with 300,000
known species.
These are also known as angiosperms and produce seed-bearing fruits.
It is believed that the flowering plant evolved from gymnosperms during the
Triassic period and the first flowering plant emerged 140 million years ago.
Flowers are the reproductive organs of the flowering plants and the most
important feature that distinguishes them from other seed plants.
The flowering plants reproduce by the process of pollination.
In this, the pollen grains transfer from the anther of the male flowers to the
stigma of the female flower where fertilization occurs and seed is formed.
Root System:
The root is a brown, nongreen and underground part of a plant. Root with
their branches is collectively called a root system. There are three types of
the root system:
Taproot System:
The taproot is mainly found in dicotyledonous plants. It develops from the
radicle of the germinating seed, along with its primary roots and branches,
giving rise to the taproot system. Mustard seeds, mangoes, grams and
banyan are a few examples of dicotyledonous plants with taproot system.
Fibrous root System:
The fibrous root is mainly found in ferns and in all monocotyledonous plants.
This root develops from thin, moderately branching roots or primary roots,
growing from the stem.
1 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, The fibrous root system usually does not penetrate deep into the soil,
therefore, on full maturity, these roots look like a mat or a carpet on the
floor. Wheat, paddy, grass, carrots, onion, grass are a few examples
of monocotyledonous plants with the fibrous root system.
The Adventitious root System:
The roots which originate from any part of the plant body other than the
radicle is called the adventitious root system.
This root system is mainly found in all monocotyledonous plants. In plants,
the adventitious root system is used for various purposes, like mechanical
support, vegetative propagation, etc.
Banyan tree, maize, oak trees, horsetails are a few examples
of monocotyledonous plants with the adventitious root system.
Stem:
The stem is the part of the plant which is found above the ground. The bark
of trees are brown in colour and younger stems are green in colour.
It forms the basis of the shoot system and bears leaves, fruits and flowers.
The region where the leaves arise is known as the node and the region
between the nodes is known as the internode.
The trunk is covered by a thick outer covering known as the bark. Overall
stem provides a definite framework and structure to a plant, which later
develops into a tree.
The stem provides support to the plant. They also protect the plant and help
in vegetative propagation. A few underground stems such as potato and
ginger are modified to store food.
The important functions of a stem include:
A stem carries out a number of functions essential for various processes such
as photosynthesis.
Provides a definite framework and structure to a plant which later develops
into a tree.
Support Primary function of the stem is to hold up buds, flowers, leaves, and
fruits to the plant.
Transportation It is the part which transports water and minerals from the
root and prepared food from leaves to other parts of the plant.
Storage Stems are one of the storerooms of plants where the prepared food
is stored in the form of starch. The stems of a few plants in the desert areas,
such as Opuntia, get modified into thick, fleshy structures that store food and
prevent excessive water loss due to transpiration.
Reproduction A few stems help in reproduction through vegetative
propagation and also help to bear flowers and to produce fruits.
The stems of a few plants in the desert areas, such as Opuntia, get modified
into thick, fleshy structures that store food and prevent excessive water loss
due to transpiration.
Leaves:
Leaves are the most important part of a plant. They contain chlorophyll that
helps the plants to prepare their food using sunlight, carbon dioxide and
water.
A leaf consists of three main parts- petiole, leaf base and lamina.
The petiole keeps the leaf blade exposed to wind and cools the leaf.
The leaf base is a protruding part of a leaf.
The lamina of the leaf contains veins and veinlets that provide rigidity to the
leaf blade and help in the transport of mineral nutrients.
2 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, Primarily, leaves have three main functions:
Photosynthesis: Green leaves prepare food for plants by using water and
carbon dioxide in the presence of sunlight. This process is called
photosynthesis.
Transpiration: Other than photosynthesis, leaves play a crucial role in the
removal of excess of water from plants through tiny pores called stomata.
This is the process of transpiration.
Reproduction: Leaves of some plants helps in reproduction also. For e.g.
leaves of Bryophyllum give rise to a new Bryophyllum plant.
Leaf and its parts
Flowers:
Flowers are the most beautiful and colourful part of a plant. They are the
reproductive part of a plant. A flower has four major parts, namely,
Petals: It is the colourful part of a flower which attracts insects and birds.
Sepals: Sepals are green leafy parts present under petals and protect the
flower buds from damage.
Stamens: This is the male part of the flower consisting of anther and
filament.
Pistil: This is the female part of the flower consisting of stigma, style and
ovary.
Fruits:
Fruits are the main features of a flowering plant.
It is a matured ovary that develops after fertilisation.
Some fruits are developed without fertilization and are known
as parthenocarpic fruits and the process is known as Parthenocarpy.
Types of Fruits:
There are three different types of fruits and are classified mainly based on
their mode of development.
Simple- Developed from the monocarpellary ovary or multicarpellary
syncarpous ovary. Examples of simple fruits.
Aggregate–Developed from the multicarpellary apocarpous ovary. Examples
of aggregate fruits.
Composite–These are false fruits, developed from the entire inflorescence
rather than from single flower. Examples of composite fruits include
blackberries, Raspberries strawberries, etc.
Seed:
A seed is a basic part of a plant, which is found enclosed within the fruit. It is
made up of a seed coat and an embryo.
During the development of the fruit, the wall of the ovary becomes the
pericarp.
In some plants, the ovary wall dries out completely, while in some it remains
fleshy.
3 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
, Types of Seeds:
Monocot: The seeds of these plants cannot be divided into two equal halves.
Dicot: The seeds of these plants can be divided into two equal halves.
Based on the number of cotyledons, seeds are further classified into two
types- dicotyledonous and monocotyledonous seeds.
Monocotyledonous— The embryo consists of an embryo axis and has only
one cotyledon.
The monocotyledonous is also known as monocot seeds. Grains including
rice, millet, wheat and other plants like onions, corn, ginger banana, palm
tree, are examples of monocot seeds.
Dicotyledonous— The embryo consists of an embryo axis and has two
cotyledons.
The dicotyledons are also known as dicots or dicot seeds. Legumes including
beans, lentils, pea, peanuts, and tomato are examples of dicot seeds.
ROOT SYSTEM :
Roots are the non-leafy part of a plant’s body that grow below the soil.
They support the plant body and help to anchor the plant to the ground.
The roots also help in the absorption of nutrients from the soil.
We also see several types of modified roots, like floating roots and aerial
roots.
Root is the descending or underground part of the plant axis.
Root is usually positively geotropic (i.e. grows downward into the soil) and
positively hydrotropic (i.e. grows towards the source of water) but negatively
phototropic
(i.e. grows away from sunlight).
Root is usually cylindrical and non-green (i.e. lack chlorophylls), but
sometimes green as in Trapa and Taeniophylum.
Root does not bear nodes, internodes, leaves or buds (exceptions are sweet
potato, wood apple etc.)
The growing point of root tip is sub-terminal and protected by a root cap or
calyptra.
Unicellular root hairs present just behind the root caps which increase the
absorptive surface area of roots,
Lateral roots are endogenous in origin i.e. arise from pericycle of the main
root.
Parts of a Root System:
The root system consists of the primary root and all its parts.
Types of Roots:
It is the primary root.
It persists throughout the lifetime of a plant.
Found in dicot plants.
This type of root grows very deep into the soil. Example: Carrot and
beetroot.
Primary Root:
It is the main trunk of the root system that grows underneath the soil layer.
All other parts of the root system emerge from the primary root.
Lateral Root:
These roots emerge horizontally from the primary root.
They grow and form the branching pattern of the root system.
4 | T.MANIKANDAN.,M.Sc.,B.Ed., Department of Botany In Unique college of Arts & Science
