- Morphology is the study of external forms of organisms.
- A flowering plant (Angiosperm) has 2 parts: Root system (underground part) & Shoot system (portion above the ground).
THE ROOT
It is the underground part formed from radicle of embryo. o Region of maturation: It is proximal to elongation zone.
Root systems are 3 types: Here, the cells
o Tap root system: It differentiate and mature.
consists of primary o Root hairs: Very fine,
roots (tap root) and its delicate, thread-like
branches (lateral roots structures formed from
such as secondary roots, epidermal cells in
tertiary roots). Seen in region behind region of
dicots. Primary root is elongation. They
elongated from radicle. absorb water and
E.g. Mustard plant. minerals from the soil.
o Fibrous root system: In Modifications of Root
monocots, primary root In some plants, roots are modified to perform functions other
is short lived and is than absorption and conduction. E.g.
replaced by many roots. o Swollen roots for food storage: E.g. Tap roots of carrot,
They originate from the turnips and adventitious roots of sweet potato.
base of stem to form fibrous root system. E.g. Wheat. o Prop roots: Hanging structures that support banyan tree.
o Adventitious root system: Roots that arise from parts o Stilt roots: The supporting roots coming out of the lower
other than radicle. E.g. Grass, Monstera and banyan tree. nodes of the stem. E.g. maize & sugarcane.
Regions of the Root o Pneumatophores: The roots that come out of the ground
o Root cap: It is the covering at the apex of root. It protects and grow vertically upwards to get oxygen for respiration.
the tender apex of the root. E.g. Rhizophora growing in swampy areas.
o Region of meristematic activity: Seen above the root cap. Functions of root
Here, the cells are very small, thin-walled and with dense ☺ Absorption of water and minerals from the soil.
protoplasm. They divide repeatedly. ☺ Provide a proper anchorage to the plant parts.
o Region of elongation: Region just above the meristematic ☺ Storage of reserve food material.
region. Here, cells undergo rapid elongation and ☺ Synthesis of plant growth regulators.
enlargement. Helps in growth of the root in length.
THE STEM
- It is the ascending part of the axis that develops from the o Thorns: Woody, straight and pointed structures developed
plumule of the embryo of a germinating seed. from axillary buds. They protect plants from browsing
- It bears branches, leaves, flowers, fruits, buds (terminal or animals. E.g. Citrus, Bougainvillea.
axillary), nodes and internodes. o Phylloclade: It is a green, flattened or fleshy cylindrical
- Nodes are the regions of the stem where leaves are born. stem containing chlorophyll for photosynthesis. Found in
Internodes are the portions between two nodes. some plants of arid regions. E.g. Opuntia (flattened stem),
- Young stem is generally green and later often become Euphorbia (cylindrical stem).
woody and dark brown. o Stolon: Slender lateral branch that arises from the base of
Functions of stem: the main axis and after growing aerially for some time arch
downwards to touch the ground. E.g. mint & jasmine.
☺ Spreading out branches bearing leaves, flowers and fruits.
o Offset: It is a lateral branch with short internodes and each
☺ It conducts water, minerals and photosynthates.
node bearing a rosette of leaves and a tuft of roots. E.g.
☺ Food storage, support, protection & vegetative propagation.
aquatic plants like Pistia and Eichhornia.
Modifications of Stem o Sucker: The lateral branches that originate from the basal
o For food storage: E.g. underground stems of potato, underground part of the main stem. It grows horizontally
ginger, turmeric, zaminkand, Colocasia etc. They also act beneath the soil and come out obliquely upward giving rise
as organs of perennation to tide over conditions to leafy shoots. E.g. Banana, Pineapple & Chrysanthemum.
unfavourable for growth.
Underground stems of grass, strawberry etc. spread to new
o Stem tendrils: Slender and spirally coiled structures
niches. When older parts die, new plants are formed.
formed from axillary buds. They help plants to climb. E.g.
Gourds (cucumber, pumpkins, watermelon) & grapevines.
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, THE LEAF
- It is a lateral, flattened structure borne on the stem. o Palmately compound leaf: In this, leaflets are attached
- It develops at the node and bears a bud in its axil. at a common point (at the tip of petiole). E.g. silk cotton.
- The axillary bud later develops into a branch.
- Leaves originate from shoot apical meristems and are
arranged in an acropetal order.
- They are important vegetative organs for photosynthesis.
A typical leaf has 3 main parts:
o Leaf base: With this, the leaf is attached to stem. It may
bear two lateral small leaf-like structures called stipules.
In monocots, the leaf base expands into a sheath covering
the stem partially or wholly. In some leguminous plants, Reticulate Parallel Pinnately
the leaf base may be swollen. It is called pulvinus. Palmately venation venation
o Petiole: It helps to hold the leaf blade to light. Long thin compound compound
flexible petioles allow leaf blades to flutter in wind, Phyllotaxy
thereby cooling leaf and bringing fresh air to leaf surface. It is the pattern of arrangement of leaves on the stem or
o Lamina (leaf
branch. It is 3 types:
blade): The green
o Alternate: In this, a single leaf arises at each node in
expanded part with alternate manner. E.g. China rose, mustard & sun flower.
veins & veinlets. The o Opposite: In this, a pair of leaves arise at each node and
middle prominent lie opposite to each other. E.g. Calotropis and guava.
vein is called o Whorled: In this, more than two leaves arise at a node and
midrib. Veins provide rigidity to lamina and act as form a whorl. E.g. Alstonia.
channels of transport for water, minerals & food materials.
Venation
- It is the arrangement of veins and veinlets in leaf lamina.
- It is 2 types:
o Reticulate venation: Here, the veinlets form a network.
It is seen in dicotyledons.
o Parallel venation: Here, the veins run parallel to each
other within a lamina. It is seen in monocotyledons.
Types of Leaves Modifications of Leaves
- Simple leaf: Here, leaf lamina is entire or when incised, the - Leaves are modified to perform functions other than
incisions do not touch the midrib. photosynthesis. E.g.
- Compound leaf: Here, the incisions of the lamina reach up o Tendrils: For climbing. E.g. peas.
to the midrib breaking it into several leaflets. o Spines: For defense. E.g. cacti.
A bud is seen in the axil of petiole in simple & compound o Fleshy leaves: To store food. E.g. onion and garlic.
leaves, but not in the axil of leaflets of the compound leaf.
- In plants such as Australian acacia, the leaves are small and
The compound leaves are 2 types.
short-lived. The petioles in these plants expand, become
o Pinnately compound leaf: In this, many leaflets are
green and synthesise food.
present on a common axis, the rachis, which represents
- Leaves of some insectivorous plants (e.g. pitcher plant,
the midrib of the leaf. E.g. neem.
Venus-fly trap) are also modified leaves.
THE FLOWER AND THE INFLORESCENCE
- A flower is a modified shoot wherein the shoot apical
meristem changes to floral meristem.
- Internodes do not elongate and the axis gets condensed.
- The apex produces different kinds of floral appendages
laterally at successive nodes instead of leaves.
- When a shoot tip transforms into a flower, it is solitary.
- The arrangement of cluster of flowers on the floral axis is
called inflorescence.
- Based on whether the apex gets converted into a flower or
continues to grow, inflorescences are 2 types: Racemose o Racemose: In this, the main axis continues to grow.
and Cymose. Flowers are borne laterally in an acropetal succession.
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- A flowering plant (Angiosperm) has 2 parts: Root system (underground part) & Shoot system (portion above the ground).
THE ROOT
It is the underground part formed from radicle of embryo. o Region of maturation: It is proximal to elongation zone.
Root systems are 3 types: Here, the cells
o Tap root system: It differentiate and mature.
consists of primary o Root hairs: Very fine,
roots (tap root) and its delicate, thread-like
branches (lateral roots structures formed from
such as secondary roots, epidermal cells in
tertiary roots). Seen in region behind region of
dicots. Primary root is elongation. They
elongated from radicle. absorb water and
E.g. Mustard plant. minerals from the soil.
o Fibrous root system: In Modifications of Root
monocots, primary root In some plants, roots are modified to perform functions other
is short lived and is than absorption and conduction. E.g.
replaced by many roots. o Swollen roots for food storage: E.g. Tap roots of carrot,
They originate from the turnips and adventitious roots of sweet potato.
base of stem to form fibrous root system. E.g. Wheat. o Prop roots: Hanging structures that support banyan tree.
o Adventitious root system: Roots that arise from parts o Stilt roots: The supporting roots coming out of the lower
other than radicle. E.g. Grass, Monstera and banyan tree. nodes of the stem. E.g. maize & sugarcane.
Regions of the Root o Pneumatophores: The roots that come out of the ground
o Root cap: It is the covering at the apex of root. It protects and grow vertically upwards to get oxygen for respiration.
the tender apex of the root. E.g. Rhizophora growing in swampy areas.
o Region of meristematic activity: Seen above the root cap. Functions of root
Here, the cells are very small, thin-walled and with dense ☺ Absorption of water and minerals from the soil.
protoplasm. They divide repeatedly. ☺ Provide a proper anchorage to the plant parts.
o Region of elongation: Region just above the meristematic ☺ Storage of reserve food material.
region. Here, cells undergo rapid elongation and ☺ Synthesis of plant growth regulators.
enlargement. Helps in growth of the root in length.
THE STEM
- It is the ascending part of the axis that develops from the o Thorns: Woody, straight and pointed structures developed
plumule of the embryo of a germinating seed. from axillary buds. They protect plants from browsing
- It bears branches, leaves, flowers, fruits, buds (terminal or animals. E.g. Citrus, Bougainvillea.
axillary), nodes and internodes. o Phylloclade: It is a green, flattened or fleshy cylindrical
- Nodes are the regions of the stem where leaves are born. stem containing chlorophyll for photosynthesis. Found in
Internodes are the portions between two nodes. some plants of arid regions. E.g. Opuntia (flattened stem),
- Young stem is generally green and later often become Euphorbia (cylindrical stem).
woody and dark brown. o Stolon: Slender lateral branch that arises from the base of
Functions of stem: the main axis and after growing aerially for some time arch
downwards to touch the ground. E.g. mint & jasmine.
☺ Spreading out branches bearing leaves, flowers and fruits.
o Offset: It is a lateral branch with short internodes and each
☺ It conducts water, minerals and photosynthates.
node bearing a rosette of leaves and a tuft of roots. E.g.
☺ Food storage, support, protection & vegetative propagation.
aquatic plants like Pistia and Eichhornia.
Modifications of Stem o Sucker: The lateral branches that originate from the basal
o For food storage: E.g. underground stems of potato, underground part of the main stem. It grows horizontally
ginger, turmeric, zaminkand, Colocasia etc. They also act beneath the soil and come out obliquely upward giving rise
as organs of perennation to tide over conditions to leafy shoots. E.g. Banana, Pineapple & Chrysanthemum.
unfavourable for growth.
Underground stems of grass, strawberry etc. spread to new
o Stem tendrils: Slender and spirally coiled structures
niches. When older parts die, new plants are formed.
formed from axillary buds. They help plants to climb. E.g.
Gourds (cucumber, pumpkins, watermelon) & grapevines.
1
, THE LEAF
- It is a lateral, flattened structure borne on the stem. o Palmately compound leaf: In this, leaflets are attached
- It develops at the node and bears a bud in its axil. at a common point (at the tip of petiole). E.g. silk cotton.
- The axillary bud later develops into a branch.
- Leaves originate from shoot apical meristems and are
arranged in an acropetal order.
- They are important vegetative organs for photosynthesis.
A typical leaf has 3 main parts:
o Leaf base: With this, the leaf is attached to stem. It may
bear two lateral small leaf-like structures called stipules.
In monocots, the leaf base expands into a sheath covering
the stem partially or wholly. In some leguminous plants, Reticulate Parallel Pinnately
the leaf base may be swollen. It is called pulvinus. Palmately venation venation
o Petiole: It helps to hold the leaf blade to light. Long thin compound compound
flexible petioles allow leaf blades to flutter in wind, Phyllotaxy
thereby cooling leaf and bringing fresh air to leaf surface. It is the pattern of arrangement of leaves on the stem or
o Lamina (leaf
branch. It is 3 types:
blade): The green
o Alternate: In this, a single leaf arises at each node in
expanded part with alternate manner. E.g. China rose, mustard & sun flower.
veins & veinlets. The o Opposite: In this, a pair of leaves arise at each node and
middle prominent lie opposite to each other. E.g. Calotropis and guava.
vein is called o Whorled: In this, more than two leaves arise at a node and
midrib. Veins provide rigidity to lamina and act as form a whorl. E.g. Alstonia.
channels of transport for water, minerals & food materials.
Venation
- It is the arrangement of veins and veinlets in leaf lamina.
- It is 2 types:
o Reticulate venation: Here, the veinlets form a network.
It is seen in dicotyledons.
o Parallel venation: Here, the veins run parallel to each
other within a lamina. It is seen in monocotyledons.
Types of Leaves Modifications of Leaves
- Simple leaf: Here, leaf lamina is entire or when incised, the - Leaves are modified to perform functions other than
incisions do not touch the midrib. photosynthesis. E.g.
- Compound leaf: Here, the incisions of the lamina reach up o Tendrils: For climbing. E.g. peas.
to the midrib breaking it into several leaflets. o Spines: For defense. E.g. cacti.
A bud is seen in the axil of petiole in simple & compound o Fleshy leaves: To store food. E.g. onion and garlic.
leaves, but not in the axil of leaflets of the compound leaf.
- In plants such as Australian acacia, the leaves are small and
The compound leaves are 2 types.
short-lived. The petioles in these plants expand, become
o Pinnately compound leaf: In this, many leaflets are
green and synthesise food.
present on a common axis, the rachis, which represents
- Leaves of some insectivorous plants (e.g. pitcher plant,
the midrib of the leaf. E.g. neem.
Venus-fly trap) are also modified leaves.
THE FLOWER AND THE INFLORESCENCE
- A flower is a modified shoot wherein the shoot apical
meristem changes to floral meristem.
- Internodes do not elongate and the axis gets condensed.
- The apex produces different kinds of floral appendages
laterally at successive nodes instead of leaves.
- When a shoot tip transforms into a flower, it is solitary.
- The arrangement of cluster of flowers on the floral axis is
called inflorescence.
- Based on whether the apex gets converted into a flower or
continues to grow, inflorescences are 2 types: Racemose o Racemose: In this, the main axis continues to grow.
and Cymose. Flowers are borne laterally in an acropetal succession.
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