Plant Tissues

A collection of cells performing a specific function is called tissue.

Plant tissues can be grouped into plant tissue systems each performing

specialized functions. A plant tissue system is defined as a functional

unit, connecting all organs of a plant. Plant tissue system is also

grouped into various tissues based on their functions. Let’s find out

more.

Types of Plant Tissues

Plant tissues can be broadly classified based on the ability of the cells

to divide into Merismatic tissue and Permanent tissue.

What is Dermal Tissue System?

Merismatic tissues consist of a group of cells that have the ability to

divide. These tissues are small, cuboidal, densely packed cells which

keep dividing to form new cells. These tissues are capable of

stretching, enlarging and differentiating into other types of tissues as

they mature. Meristematic tissues give rise to permanent tissues.

Merismatic tissues can be of three types depending on the region

where they are present: Apical meristems, lateral meristems, and

intercalary meristems.

Permanent tissues are derived from the merismatic tissues and have

lost their ability to divide. They have attained their mature form. They

are further classified into two types: Simple and complex permanent

tissues.

Browse more Topics under Anatomy Of Flowering Plants

● Tissue System

● Stem

● Leaf

● Inflorescence

● Secondary Growth

● Flower

● The Fruit

● The Seed

● Classification of Flowering Plants

● Anatomy of Dicotyledonous and Monocotyledonous Plants

Permanent Tissues

The permanent tissues form the major portion of the plant.

Simple Permanent tissues ● Parenchyma– These tissues are found in the soft parts of a plant

such as the roots, stems, leaves, and flowers. The cells of this

tissue are loosely packed and contain large intercellular spaces

between them. Each cell has a vacuole at the center. The

functions of parenchyma tissues are storage, photosynthesis,

and to help the plant float on water.

● Collenchyma- Are similar to parenchyma cells with thicker cell

walls. They are meant to provide mechanical support to the

plant structure in parts such as petiole of the leaf.

● Sclerenchyma- The cells of this tissue are dead. They are rigid,

contain thick and lignified secondary walls. Their main

function is to provide strength and support to parts of the plant.

Complex Permanent Tissue

Unlike simple permanent cells which look the same and are made up

of one type of cells, complex permanent tissues are made up of more

than one type of cells. These different types of cells coordinate to

perform a function. Xylem and Phloem are complex permanent tissues

and are found in the vascular bundles in the plants.

Xylem- It consists of tracheids, vessels, xylem parenchyma and xylem

fibres. Tracheids and vessels are hollow tube-like structures that help

in conducting water and minerals. The xylem conducts only in one

direction i.e vertically. The xylem parenchyma is responsible for

storing the prepared food and assists in the conduction of water.

Xylem fibres are supportive in function.

Phloem- It consists of four of elements: sieve tubes, companion cells,

phloem fibres and the phloem parenchyma. Unlike the xylem, phloem

conducts in both directions. It is responsible for transporting food

from the leaves to the other parts of the plant. Phloem contains living

tissues except for fibres that are dead tissues.

Functions of plant tissues Plant tissues have different functions depending upon their structure and

location

● Help provide mechanical strength to organs.

● They help in providing the elasticity and flexibility to the

organs.

● They help the tissues to bend easily in various parts of a plant

like- leaf, stem, and branches without damaging the plant

● The xylem and phloem tissues help in transportation of

material throughout the plants

● They divide to produce new cells and help in the growth of the

plants.

● They help in various cellular metabolisms like photosynthesis,

regeneration, respiration, etc.

Anatomy of Dicotyledonous and Monocotyledonous Plants

Solved Example for You

Q: Pick the odd one out.

(a) sieve tubes (b) companion cells

(c) phloem fibres (d) Tracheids

Sol. (d) Tracheids

The odd one out is option (d) tracheids as they are a part of xylem

tissue whereas the other three options are parts of phloem tissue.

Stem: Functions, Structure, and Types

The main functions of stems are to support and elevation of leaves,

fruits, and flowers. Stem arranges leaves in a way that it gets direct

sunlight to perform photosynthesis. Xylem and Phloem conduct water

across the plant. Stems stores food, water, and nutrients. Cells of a

stem, meristems, produce new living tissues. Underground stem,

Aerial stem, and subaerial stem are three different types of Stem. A

stem has many important functions it performs other than letting you

climb a tree. Let us take an in-depth look at the stem of plants.

A plant stem is one of the two main structural axes of a vascular plant.

It is the part of the plant that lies above the ground. Few stems are also

found underground and are considered to be stem modifications.

Functions of Stem

● It supports and holds leaves, flowers, and fruits.

● The stem allows the leaves to arrange in a way that they are

able to receive direct sunlight in order to efficiently perform

photosynthesis. The arrangement and position of leaves also

allow for gas exchange.

● The xylem and phloem present in the vascular bundles of stems

conduct water and minerals across the plant.

● Stems bear flowers and fruits in a position that facilitates the

processes of pollination, fertilization, and dispersion of seeds.

● Some stems undergo modification to store food and water.

Example: succulents.

● Few green stems contain chloroplasts and are capable of

carrying out photosynthesis as well.

● Some stems are modified to carry out vegetative propagation

which is a form of asexual reproduction seen in plants.

Browse more Topics under Anatomy Of Flowering Plants

● Plant Tissues

● Tissue System

● Leaf

● Inflorescence

● Secondary Growth

● Flower

● The Fruit

● The Seed

● Classification of Flowering Plants

● Anatomy of Dicotyledonous and Monocotyledonous Plants

Structure of a Stem

The stem divides into nodes and internodes. The nodes give rise to the

leaves and hold the buds which grow into branches. The internodes

separate two nodes.

Internally, it contains three basic types of tissues: Dermal tissue,

Ground tissue, and Vascular tissue all of which are made of simple

cells.

● Epidermis: The epidermis is a single layer of cells that make up

the external tissue of the stem called dermal tissue. This tissue

covers the stem and protects the underlying tissue. Woody

plants have an extra layer of protection on top of the epidermis

known as bark. In some cases, the bears’ multi-cellular hairs

and a few stomata.

● Ground tissue divides into two- the central portion is known as

the pith and the cortex which lies between the vascular tissue

and the epidermis.

Learn more about the concept of the Tissue System here in detail.

The cortex can be further divided into three layers:

● Hypodermis: It is the outermost layer of the cortex. It is formed

of 4 to 5 cell thick layer of collenchymatous cells. These cells

are living and contain chloroplasts.

● General cortex: Lies below the hypodermis. It consists of

thin-walled parenchymatous cells with intercellular spaces.

Some of the cells have chloroplasts and are known as

chlorenchyma.

● Endodermis: The innermost layer of the cortex. It is made up of

a single row of compact barrel-shaped cells without

intercellular spaces. The cells of endodermis store starch grains

and so they are known as the starch sheath. Casparian strips are

distinctly visible in endodermal cells.

● The vascular tissue of the stem consists of the complex tissues

xylem and phloem which carry water and nutrients up and

down the length of the stem and are arranged in distinct strands

called vascular bundles. Cambium is a strip of thin-walled cells

that lie between the xylem and phloem in dicot plants.

Cambium is made up of merismatic cells and is responsible for

secondary growth. It is absent in monocots.

What are Plant Tissues?

Growth in a Stem

Growth in stems occurs in two ways:

● Primary growth occurs at the apical tips of the stem by virtue of

the rapidly dividing merismatic tissue in these regions of the

stem.

● Secondary growth is actually the increase in the thickness of

the stem by virtue of the lateral meristems. These are absent in

the herbaceous plants as they lack cambium which is

responsible for this type of growth.

Types of Stems

Based on their location with respect to the ground, there are three

types of stems:

● Underground stem

● Aerial stem

● Subaerial stem.

Understand Tissue System

Underground stems

These stems remain at the ground level and produce aerial shoots that

rise above the soil. Their roots are superficially present. These stems

are meant for storage of food and perennation. These stems are also

capable of vegetative propagation.

They are of different types as follows:

● Rhizome- is a thickened underground stem that has distinct

nodes and internodes and scaly leaves at the nodes. Example:

Ginger.

● Tuber- is a horizontal underground stem that becomes enlarged

at its growing tips due to the accumulation of stored food,

commonly starch. E.g. Potato.

● Bulb- It is a short underground stem with a fleshy base with

leafy scales. The stem is actually reduced to form a disc-like

structure. The nodes bear fleshy scales. On the upper side, the

disc bears a terminal bud surrounded by a number of leaves. E

.g. Onion.

● Corm- is a short, vertical, swollen underground stem of a plant

that serves as a food storage organ to enable the plant to

survive adverse conditions. E.g Colocasia

Know more about Secondary Growth

Subaerial Stems

These stems run parallel to the ground and give off roots at certain

intervals or nodes.

They are further divided into the following types:

● Runner- It grows parallel to the ground and has a creeping stem

with long internodes. On the lower surface, the nodes give out

adventitious roots at regular intervals. A runner develops from

the axils of lower leaves of the aerial stem

● Offset- These are shorter and thicker than the runner and are

often seen in aquatic plants

● Stolon- It is similar to a runner but arises from the lower part of

the main axis.

● Sucker- These stems are similar to the stolon but it grows

obliquely upwards and gives rise to a new plant

What is Inflorescence?

Aerial Stems

These stems are found above the ground and perform varied functions.

They are of the following types:

● Thorns- These stem modifications appear as hard, woody and

sharp outgrowths that protect the plant. example: roses

● Tendril – These types of stems are slender, twining strands that

enable a plant to seek support while climbing on other surfaces.

● Phylloclade- This type of stem is a green, flattened or

cylindrical one that resembles a leaf. A phylloclade is capable

of performing photosynthesis and we can find them in

xerophytes or in other plants that have little or no leaves.

● Cladode- This is a modification of the phylloclade where it

contains one or more internodes.

● Bulbil- These stems are actually modified axillary buds which

become fleshy and rounded due to the storage of food. They

become detached from the plant, fall o the ground and develop

into a new plant, thus help in vegetative propagation.

Solved Example for You

Q: What kind of a stem is a potato?

a. Tuber

b. Tendril

c. Bulbil

d. Rhizome

Sol: The correct option is (a) Tuber

A potato is an underground modification of a stem and it stores food

in the form of starch. This type of stem modification is called a tuber.

Leaf

A leaf is actually called ‘the kitchen of the plant’. This is because

they are the main organ responsible for photosynthesis, through which

the plant produces its energy a.k.a. it’s food. They obtain their green

color due to the presence of chlorophyll. Let us learn more about

them.

Leaf

A leaf is the green, flat lateral outgrowth in plants. They come in

different shapes, sizes, and colors, and are generally dorso-ventrally

flattened and thin. They are the main organ responsible for

photosynthesis as they contain chlorophyll.

Browse more Topics under Anatomy Of Flowering Plants

● Plant Tissues

● Tissue System

● Stem

● Inflorescence

● Secondary Growth

● Flower

● The Fruit

● The Seed

● Classification of Flowering Plants

● Anatomy of Dicotyledonous and Monocotyledonous Plants

Parts of a Leaf

Leaves have two main parts: The leaf blade and the Stalk or the

petiole.

● The leaf blade: It is also called the lamina. It’s generally broad

and flat. It is in this layer that photosynthesis occurs. It contains

a prominent midrib at the center of the leaf blade which is the

main vein. From this midrib arise branches called veins. They

are of different types depending upon the type of edges, the

pattern of the veins and the number of blades per leaf.

● The petiole: It is the stalk-like structure which connects the leaf

blade to the stem. The petiole has tiny tubes, that connect the

veins on the leaf blade to the stem. Few of these enable water

transport to the leaf while the other carry food away from the

leaf to other parts of the plant.

Some plants also contain another part called stipules. These are small

flap-like structures that grow at the base of the petioles. They are

protective in some plants when they protect the growing petiole while

in others, they fall off once the petiole starts growing.

Do you know about SEED ?

Types of Leaves

Leaves can be classified based on many anatomic and morphologic

features:

Based on Blade

● Simple Leaf- the lamina or the leaf blade is undivided. Even if

there are small divisions, they do not reach the midrib and

divide the lamina.

● Compound Leaf- The leaf blade is divided from the midrib into

two or more parts. Sometimes these divided parts function as

separate leaves.

Based on Shape of the Blade

● Elliptical

● Lanceolate

● Linear

● Ovate

● Cordate

Want to know about Plant Tissues ?

Based on the presence or absence of the petiole (stalk)

● Petiolated- These leaves have a stalk or petiole which attaches

them to the stem.

● Sessile- These leaves do not have a petiole and are directly

attached to the stem.

Based on the serration on the edge of the leaf blade

● Smooth: This type of leaf margin is called ‘entire’ leaf margin

and is smooth all around

● Sinuate: Have smooth curves along the margins

● Dentate: They have teethed margins

● Serrate: Have saw-teeth shaped margins

● Lobed: the leaf blade is divided but the division doesn’t reach

the midrib

Based on the arrangement of veins

● Parallel: The veins on the leaf blade run parallel to each other

maintaining the same distance throughout.

● Palmate: The veins originate at a point and diverge from the

point similar to the palm of the hand

● Pinnate: There is a midrib which is present in the middle of the

leaf blade. From this midrib arise the lateral veins.

Based on their arrangement on the stem

● Alternate: Each leaf arises from a separate node on the stem at

different levels

● Opposite: Each node gives rise to two leaves, one on each side

placed oppositely.

● Whorled: In this arrangement, several leaves are present at the

same level around the stem giving it a whorled appearance.

● Rosulate: The leaves arrange themselves in a ring-like pattern

around the stem.

Structure of a leaf

(Source: Wikipedia)

Each leaf consists of the following layers.

● Epidermis: It is the outermost layer and secretes a waxy

substance called the cuticle. The cuticle helps retain water

inside the leaf cells. The epidermis houses the guard cells

which regulate the movement of water into and outside the cell.

Guard cells do so by controlling the size of the pores also

called stomata.

● Mesophyll: This forms the middle layer of the leaf. It is

differentiated into two layers depending on the type of cells

found: palisade and spongy mesophyll layers. It is in this layer

that the chloroplasts are found. Chloroplasts are cell organelles

that contain chlorophyll which is required for photosynthesis.

The vascular tissues of the leaf are contained in the irregularly

arranged spongy mesophyll cells.

● Vascular Tissue: The vascular tissue is actually found in the

veins of the leaf. The vascular tissues are composed of xylem

and phloem which are responsible for the transport of water

and food.

Learn more to understand the concept of Tissue here in detail.

Functions of a Leaf

● Photosynthesis: This is the most important function of a leaf.

They contain chloroplasts which have the pigment chlorophyll

that is responsible for helping in photosynthesis. The prepared

food is transported to the other parts of the plant via phloem

tissue.

● Helps the plant breathe: The epidermis of the leaf contains

guard cells that control and regulate the small pores on the

undersurface of the leaves. These pores are called stomata.

Stomata are responsible for regulating water in and out of the

cell. It is also responsible for the exchange of gases across the

epidermis.

● Storage of food: In some plants, the leaves are modified to

store food. These plants generally have succulent leaves as seen

in xerophytic plants.

Solved Example for You

Q: Which structure of the leaves helps in gaseous exchange?

a. Stomata

b. Petiole

c. Spongy mesophyll

d. Xylem

Sol: The correct option is (a) Stomata

Stomata are small pores that are found in the lower epidermal layer of

the leaf blade. They are regulated by the guard cells. The stomata help

in regulating water intake and output across the cells and help in

exchange of gases across them too.

Inflorescence

Flowers are the reproductive parts of a plant. They are bright in colour

and attractive to attract pollinators to it. Flowers can be present

solitarily or in bunches or clusters. Clustered flowers can be found

arranged on branches different from the other branches of the plant.

These clusters of flowers are known as an inflorescence and each

individual flowers in it are known as florets.

Parts of an Inflorescence

An inflorescence has the following parts:

a)Peduncle: It is the main supporting stalk of the inflorescence.

b)Pedicle: It is the stalk of the individual flowers. Some flowers are

sessile and do not have a stalk, they are directly attached to the

peduncle.

c)Bracts: These are small green petal-like structures that are found

near the peduncle. They are similar to the sepals in a flower.

d)Flower/Flowers: These rest atop the pedicle or the main stalk.

Learn more about Stem Structure here in detail.

Types of Inflorescence

It can be broadly classified based on the following:

1. Number and position of flowers

2. Sequence of flower development, and

3. The nature of inflorescence branching

They are commonly classified and studied under two categories:

Racemose and Cymose inflorescence.

Racemose Inflorescence

In this type, the axis of the inflorescence has unlimited growth. The

flowers are arranged in acropetal manner which means that the older

flowers are present at the base while the younger ones are present

towards the top. The individual flowers may be sessile or pedunculate.

(Source: Wikipedia)

The different types of the racemose inflorescence are:

● Raceme-Flowers with pedicel and are in an acropetal

arrangement. Example: mustard

● Spike- Flowers without pedicel and are in an acropetal

arrangement. Example: Barley

● Umbel- Pedicilate flowers in which the flowers originate from

the same place and reach the same level. Example Waxflowers

● Corymb- Unlike in the Umbel, the corymb consists of

pedicilate flowers where the length of pedicels of the lower

flowers is more than that of the upper ones such that all the

flowers come up to the same level. They have an umbrella

appearance when seen from the top. Example: Hawthorn

● Spadix- when a spike is covered sheath-like covering by a

spathe it becomes a spadix. Example: Banana

● Capitulum- It is actually a short spike where the flowers are

directly placed on the peduncle and giving it a flower-like

appearance. A smaller capitulum is called the head. Example:

Dandelion, sunflower.

Learn more about Tissue System here in detail.

Cymose Inflorescence

(Source: Wikipedia)

In a cymose inflorescence, the axis has limited growth and the flowers

are arranged in a basipetal manner which means that the older flowers

are found towards the top and the younger ones towards the base of

the axis.

The different types of the cymose inflorescence are:

● Monochasial/Uniparous– the main axis ends in a flower and

has one lateral branch. Example: Drosera

● Dichasial/Biparous– The main axis produces a flower at the tip

and produces two branches simultaneously at a lower level

both of which also end in flowers. This pattern of branching is

further repeated. Example: Dianthus

● Polychasial/ Multiparous– The main axis ends in a flower and

at the same time it produces a number of lateral flowers around.

The oldest flower lies in the centre and ends the main floral

axis. Example: Calotropis

● Cymose Capitulum– In this case, the peduncle is reduced to

form a disc-like structure. This disc bears sessile flowers with

the oldest in the centre and the younger ones towards the

periphery.

Solved Example for You

Q: Which of the following type of inflorescence has an axis with

limited growth?

(a) Drosera (b) Sunflower

(c) Mustard (d) Barley

Sol. (a) Drosera

Axis with limited growth is seen in the cymose type. Drosera is a

cymose inflorescence whereas the other three are racemose(have

unlimited growth of axis). Therefore, the correct answer is option a.

Secondary Growth

Do you know how the age of a tree is calculated? Well, we simply

count the annual rings that form in its trunk due to the wood growth.

This lateral expansion or growth of a tree is called Secondary Growth.

Lets us learn about it here.

Secondary Growth

Growth in plants occurs in two ways: primary and secondary.

● Primary growth causes the plant to grow in length, both below

and above the ground, due to the apical meristems that are

actively dividing into these regions.

● Secondary growth causes the plant to grow in width due to the

presence of lateral meristems or cambium layer which actively

divides to bring about this kind of growth.

We need to understand that secondary growth occurs in both stems as

well as roots.

Browse more Topics under Anatomy Of Flowering Plants

● Plant Tissues

● Tissue System

● Stem

● Leaf

● Inflorescence

● Flower

● The Fruit

● The Seed

● Classification of Flowering Plants

● Anatomy of Dicotyledonous and Monocotyledonous Plants

Secondary growth in stems

(Source: BiologyDisscussion)

As mentioned earlier, secondary growth occurs due to the lateral

meristems that divide similar to the apical meristems.The cells of the

lateral meristems divide rapidly and grow outwards laterally rather

than apically as in case of primary growth. The lateral meristems that

cause secondary growth are known as cambium. This layer of

cambium is present in dicots but absent in monocots.

Two layers of Cambium

Cork Cambium: The cork cambium makes a tough, insulating layer of

cells called as cork. These cells have wax in them, which helps them

protect the stem from water loss. Cork is also a part of the bark.

Vascular Cambium: The vascular cambium produces vascular tissue

(xylem and phloem), which provide additional support for the shoot

system in along with transporting water and nutrients. The xylem and

phloem that arise from the vascular cambium replace the original

(primary) xylem and phloem, and so are called as secondary xylem

and secondary phloem. They add to the width of the plant. The

vascular cambium is only single layer in thickness and adds xylem on

the inside and phloem on the outside of it. In trees, the secondary

xylem forms the wood and the secondary phloem forms the bark.

In cases of monocots, who lack cambium, secondary growth is not

seen. The stems do not get as wide as in the dicots.

Secondary growth in roots

(Source: UCD)

Secondary growth in roots leads to increase in the thickness of the

root. This happens by the addition of vascular tissue.

Initiation of secondary growth takes place in the zone of maturation

soon after the cells stop elongating there. The vascular cambium

differentiates between the primary xylem and phloem in this zone. The

pericycle is a cylinder of parenchyma or sclerenchyma or cells that

lies just inside the endodermis and is the outer most part of the stele of

plants.The pericycle cells divide simultaneously with the procambium.

As a result, a cylinder of cambium is formed that encircles the primary

xylem. Similar to the stem, the xylem is formed on the inside and the

phloem towards the outside of the cambium.

Some roots form an outer protective layer called the periderm which

originates from the pericycle and replaces the epidermis. The

pericycle resumes its meristematic character and begins to divide

periclinally again. At this point, it is called the phellogen or the cork

cambium. This cork cambium forms cork cells towards the outside of

the plant. They are suberized which makes the cells impermeable to

water.

Solved Example for You

Q: Which part of the vascular cambium forms the bark in trees?

(a) Endodermis (b) Secondary phloem

(c) Pericycle (d) Secondary xylem

Sol. (b) Secondary phloem

It is the secondary phloem of the vascular cambium of dicot stems that

forms the bark of trees. The secondary phloem forms the wood.

Flower

Did you know the largest flower found on earth weighs fifteen pounds

and can grow up to three feet! It is called the Rafflesia Arnoldii. And

the smallest is the Wolffia and it is the size of a grain of rice. Flowers

are more than pretty things, they are responsible for the reproduction

of plants and are absolutely essential. Let us learn more about them.

Plants are majorly classified on basis of presence or absence of flower

into flowering and non- flowering plants. A flower is a characteristic

feature of flowering plants and is actually an extension of the shoot

meant for reproduction. Flowers are attractive and appear in different

colours and shapes to attract pollinators who help in pollen transfer.

Browse more Topics under Anatomy Of Flowering Plants

● Plant Tissues

● Tissue System

● Stem

● Leaf

● Inflorescence

● Secondary Growth

● The Fruit

● The Seed

● Classification of Flowering Plants

● Anatomy of Dicotyledonous and Monocotyledonous Plants

Parts of a Flower

(Source: anmh.org)

Most flowers have four main parts: sepals, petals, stamens, and

carpels. The stamens are the male part whereas the carpels are the

female part of the flower. Most flowers are hermaphrodite where they

contain both male and female parts. Others may contain one of the two

parts and may be male or female.

Before getting into parts, understand the classification of Flowers

here.

● Peduncle: This is the stalk of the flower.

● Receptacle: It is that part of the flower to which the stalk is

attached to. It is small and found at the centre of the base of the

flower.

● Sepals: These are the small, leaf-like parts growing at the base

of the petals. They form the outermost whorl of the flower.

Collectively, sepals are known as the calyx. The main function

of the calyx and its sepals is to protect the flower before it

blossoms(in the bud stage).

● Petals: This layer lies just above the sepal layer. They are often

bright in colour as their main function is to attract pollinators

such as insects, butterflies etc to the flower. The petals are

collectively known as the corolla.

● Stamens: These are the male parts of a flower. Many stamens

are collectively known as the androecium. They are

structurally divided into two parts:

○ Filament: the part that is long and slender and

attached the anther to the flower.

○ Anthers: It is the head of the stamen and is responsible

for producing the pollen which is transferred to the

pistil or female parts of the same or another flower to

bring about fertilization.

(Source: Wikipedia)

● Pistil: This forms the female parts of a flower. A collection of

pistils is called the gynoecium.

Learn more about Inflorescence here.

Pistil consists of four parts

(Source: Britannica)

a. Style -is a long slender stalk that holds the stigma. Once the

pollen reaches the stigma, the style starts to become hollow and

forms a tube called the pollen tube which takes the pollen to the

ovaries to enable fertilization.

b. Stigma– This is found at the tip of the style. It forms the head

of the pistil. The stigma contains a sticky substance whose job

is to catch pollen grains from different pollinators or those

dispersed through the wind. They are responsible to begin the

process of fertilization.

c. Ovary – They form the base of the pistil. The ovary holds the

ovules.

d. Ovules– These are the egg cells of a flower. They are contained

in the ovary. In the event of a favorable pollination where a

compatible pollen reaches the stigma and eventually reaches

the ovary to fuse with the ovules, this fertilized product forms

the fruit and the ovules become the seeds of the fruit.

Introduction to Leaf Structure

Solved Example for You

Q: What forms the androecium in a flower?

a. Petals

b. Stamens

c. Sepals

d. Pistil

Sol: The correct option is (b) Stamens

The androecium is the male part of the flower. A collection of stamens

is an androecium.

The Fruit

Everybody likes fruits! Fruits are a characteristic of flowering plants.

Once pollination and fertilization occur, the ovary of the plant

becomes the fruit and the ovules become the seeds. They can be fleshy

or dry. Let’s learn more about them.

The main purpose of fruits is that they protect the seeds during

development. Since they are often colourful and emanate a delectable

odour, they help in attracting birds and other animals to eat seeds. This

way the seeds get dispersed to other areas for generating new plants.

Structure of a fruit

The fruit primarily contains two parts: the pericarp and the seed. The

pericarp layer is actually the outer wall of the ovary from which the

fruit developed. The pericarp has three layers:

Source: Google

● Exocarp or Epicarp: This is the outermost layer of the pericarp

that forms the skin.

● Mesocarp: It is the thick, fleshy and juicy middle layer of the

pericarp.

● Endocarp: It is the innermost layer of the fruit which often

develops into the pith.

Classification of Fruits

On basis of the number of ovaries and the number of flowers involved

in their formation, fruits are broadly classified into three categories:

● Simple Fruits

● Aggregate Fruits

● Multiple Fruits

Source: Backyard Nature(google)

Simple Fruits

● These fruits develop from a single ovary of one or more

carpels.

● These fruits are further divided into Dry fruits and Fleshy fruits

depending upon pericarp.

Dry Fruits

In these fruits, the pericarp is not succulent and the pericarp becomes

dry one the fruits mature. Dry fruits are of two types: Dehiscent and

Indehiscent.

a. Dehiscent fruits: These fruits dehisce or split open when they

mature. Types of dehiscent dry fruits are:

Source: Google

● Follicle- is a dry dehiscent fruit which arises from a single

carpal and on maturity splits only along one suture. E.g.

Larkspur

● Legume- is a dry dehiscent fruit which arises from a single

carpal and on maturity splits along its dorsal and ventral

sutures. E.g. Pea

● Capsule- made up of multiple carpals and splits in four ways.

E.g Eucalyptus

● Silique- is made up of two carpals that split on maturity. E. g

Mustard plant

b. Indehiscent fruits: These fruits do not split open on maturity. Types

of indehiscent dry fruits are:

Source: Google

● Akene- where the only seed is attached to the fruit at one point

only. E.g. sunflower

● Caryopsis- where the only seed is attached to the fruit at all

possible points. E.g. Maize

● Samara- is a one or two seeded which has seeds with wing-like

structures. E.g.Maple

● Schizocarp- is made up of multiple carpals which separate on

maturity to form multiple indehiscent fruits. E.g. Dill

● Nut- has thick pericarps and is a one-seeded fruit formed from

a compound ovary. It is hard in texture. E.g Chestnuts

Fleshy Fruits

In these fruits, the fruit wall or pericarp is thick and fleshy. They are

of the following types:

Source: Google

● Berry is made up of one or more carpals and contains one or

more seeds. The pericarp is soft, fleshy and juicy. E.g Banana,

grapes

● Drupe is derived from a single carpel and containing one seed.

Exocarp is present as a thin skin, the mesocarp is fleshy and the

endocarp becomes stony hard. E.g Mango

● Pome (accessory fruit) is an accessory fleshy fruit formed by a

group of carpels that are firmly united with each other and

surrounded by and united to the receptacle. E.g Apple

Aggregate Fruits

These fruits develop from multiple ovaries but of the same flower. So,

an aggregate fruit consists of a collection of simple fruits called

fruitlets. E.g Blackberries, strawberries.

Multiple Fruits

They are formed by all the flowers of an inflorescence which together

result in a single big fruit. Multiple fruits are called false or composite

fruits. E.g Mulberries, pineapple.

Solved Example for You

Q: Which of the following types of fruit has seeds with wing-like

structures?

(a) Akene (b) Capsule

(c) Samara (d) Caryopsis

Sol. (c) Samara

Samara is a simple dry indehiscent which is made up of one or two

seeds which have a wing-like structure.

The Seed

The seed in a plant is the part that develops from the ovules after

fertilization. They are enclosed in the fruit which develops from the

fertilized ovary. The seeds are formed as a result of sexual

reproduction and contain the young embryo which can develop into a

new plant. Let’s learn more.

Structure of a Seed

Seeds of different plants may vary in many ways, but the basic

anatomy remains the same. A typical seed consists of the following

parts:

Source: Google

● Tesla: It is the outer coat of the seed that protects the

embryonic plant.

● Micropyle: It is a tiny pore in the testa that lies on the opposite

of the tip of the radicle. It permits water to enter the embryo

before active germination.

● Hilum: Is a scar left by the stalk which attached the ovule to the

ovary wall before it became a seed.

● Cotyledon: In some plants, this contains high quantities of

starch and will provide a source of food for the developing

embryo prior to germination, in other plants this role is

performed by an endosperm. In monocotyledons, there is just

one cotyledon whereas in dicotyledons there are two.

Depending on the type of germination (epigeous or hypogeous)

the cotyledons may remain below ground or be pulled above

ground.

● Radicle: This is the embryonic root which will develop into the

primary root of the plant. It is usually the first part of the

embryo to push its way out of the seed during germination.

● Plumule: This is the embryonic shoot. It appears as a bud

which will give rise to the shoot and the remaining structures in

the plant.

● Endosperm: In many plants, a separate part for storage of

starch develops and this is called the endosperm. It is seen in

maize and wheat.

Learn more about Stem Structure here in detail.

Functions of Seeds

The seeds perform the following functions:

● They help in germination of the new plant.

● The seeds contain food reservoirs in the form of cotyledons and

endosperm.

● The seed coat is protective in nature which protects the embryo

inside.

Dispersion of Seeds

Dispersion is defined as the scattering or transport of seeds from one

place to another by means of a dispersing agent. It can occur by four

modes:

● Wind

● Water

● Animals

● Explosion

Dispersion by Wind

The seeds that are dispersed by wind are generally light and small

such that they can be easily carried away by the wind. Example:

cotton seeds

Source: Google(Tes.com)

Dispersion by Animals

These seeds have external structures such as spines or hooks such that

they can attach themselves to animals and get dispersed to other

places. These seeds are generally attractive and so are their fruits.

Example: Guava seeds, dates.

Dispersion by Water

These seeds have a structure, generally, hollow such that they can

easily float on water. Once they reach a place where the conditions are

suitable, they germinate. Example: Mangroves.

Source: Google

Dispersion due to Explosion/Expulsion

Some plants fling or throw their seeds out once the fruit has ripened.

This explosion occurs as a result of evaporation of water from the

pods. Once the pods dry out, they expel the seeds which are then

carried by wind or gravity to other places where they germinate.

Example: Viola

Source: Pinterest

Solved Example for You

Q: Which of the following parts does the seed develop from?

(a) Ovary (b) Embryo

(c) Embryo sac (d) Ovule

Sol. (d) Ovule

Once fertilization occurs, the ovary starts maturing and eventually

develops into the fruit and the ovules contained in them become the

seeds.

Classification of Flowering Plants

Plants are the primary food producers of the food chain. What are

different types of flowers? They can be classified in many different

ways: Based on presence or absence of seeds, Based on whether the

plants produce flowers or not, Based on the presence of stems, leaves,

and roots. The most accepted and popular classification of plants is

based on whether they are flowering plants (angiosperms) or

non-flowering plants (gymnosperms).

Lets us understand the classification of Angiosperms or flowering

plants.

Classification of Angiosperms

A large number of plants fall into this category and so there was a

requirement to classify angiosperms. There are three systems that

classify angiosperms:

● Artificial Systems based on superficial features.

● Natural systems based on form relationships.

● Phylogenetic systems based on evolutionary and genetic

relationships.

Artificial systems

These systems of classification were based on one or few

morphological characters. Many botanists used this system and

classified angiosperms into different classes. Few of these botanists

are

● Theophrastus- who is known as the father of botany and

apparently the first to provide a difference between dicots and

monocots.

● John Ray- His system was more advanced than the earlier

systems

● Carolus Linnaeus- Introduced the binomial system of naming

Natural Systems

These systems the plants were classified on the basis of their natural

affinities (i.e. the basic similarities in the morphology) rather than on a

character for determining the affinities. Compared to the artificial

systems, it was based on the proper utilization of all facts and figures

available in nature. In this system, the plants were grouped and placed

into different taxa like classes, orders, families, and genera. Michel

Adanson was the first scientist to reject all the artificial systems and

support the natural systems of classification. The main demerit of this

system was that the classification was not based on evolutionary

relationships. Different families had been placed in specific groups

which do not show any evolutionary relationships.

Learn more about the Anatomy of Fruits here.

Phylogenetic systems

These classification systems came up after Darwin’s theory of

evolution was proposed and widely accepted.

There were two popular systems:

Engler and Prantl: They arranged flowering plants according to

increasing complexity of their floral morphology. Their system

considered monocots as more primitive than dicots.

Hutchinson: He proposed the most widely used classification which is

also known as the ‘Hutchinson’s classification’.

The Hutchinson’s classification broadly divided angiosperms into:

● Dicotyledons

● Monocotyledons

Dicotyledons/ Dicotyledonous plants

These are flowering plants which have two cotyledons in their seeds.

Endosperm may or may not be present in the seed.

The following are the features of dicots:

Roots: They have a tap root system with smaller secondary roots

originating from it. Due to its tap root system, they can penetrate

deeper into the soil to find water and minerals required for its growth.

Leaves: They have reticulate venation also called net venation on their

leaves. They have a stalk that attaches the leaves to the stem. Learn

the structure and different types of Leaves here with video.

Vascular system: Cambium is present which helps in secondary

growth of the stem.

Stems: The stems are hollow and the plants are generally herbaceous

or woody.

Flowers: The parts of the flowers usually exist in numbers of fours or

fives. Learn more about the parts and structure of Flowers here in

detail.

Dicotyledons are further divided into- Lignosae and Herbaca.

Monocots/ Monocotyledonous Plants

These flowering plants have a single cotyledon in their seeds.

Endosperm is always present in the seed.

Roots: They have a fibrous root system.

Leaves: Their leaves have parallel venation and the leaves are sessile

i.e they do not have a stalk which attaches the leaf to the stem.

Vascular System: Cambium is absent and so there is no secondary

growth of the stem.

Flowers: the parts of the flowers exist in numbers of three.

The two divisions of Monocotyledons- Calciflorae, Corolliferae,

Glumiflorae.

Learn Anatomy of Dicotyledonous and Monocotyledonous Plants in

more detail here.

Solved Example for You

Q: Which is the most accepted system of classification?

(a) Artificial systems (b) Natural system

(c) Hutchinson’s system (d) Englar and Prantl system

Sol. (c) Hutchinson’s system

Hutchinson’s

system is a phylogenetic system that classified plants. It was

systematic, and grouped plants based on evolution along with features.

Anatomy of Dicotyledonous and Monocotyledonous Plants

Tulips and daisies are both beautiful flowering plants. However, they

do not fall into the same category of plants. Flowering plants are

actually classified into two categories based on their embryo, called

Monocotyledonous (monocot) plants and Dicotyledonous plants. Let

us find out more about these plants.

Dicotyledonous and Monocotyledonous Plants

Plants can be broadly classified into flowering and non-flowering

plants. Flowering plants are called as angiosperms while non-

flowering plants are known as gymnosperms. Angiosperms are further

classified based on the nature of the embryo in the seed into

Monocotyledonous and Dicotyledonous plants.

Dicots are plants that have seeds with two cotyledons and so are

termed as dicotyledonous plants. Examples: Sunflower, Mango

Monocots are plants that have seeds with one cotyledon and so they

are called as monocotyledonous (monocot) plants. Example:

Sugarcane, Maize

Browse more Topics under Anatomy Of Flowering Plants

● Plant Tissues

● Tissue System

● Stem

● Leaf

● Inflorescence

● Secondary Growth

● Flower

● The Fruit

● The Seed

● Classification of Flowering Plants

Anatomy of Dicotyledonous and Monocotyledonous Plants

Both sets of plants differ structural features: Stems, leaves, flowers,

and roots.

Dicotyledonous Plants

(Source: Plantlist)

Roots

● These plants have a tap root system

● They have two layers: the outermost epidermis which

sometimes forms root hairs, the inner endodermis or the cortex.

● The epidermis consists of loosely packed cells whereas the

endodermis has tightly packed cells.

● The central pith is inconspicuous.

Stems

● Stems are usually solid

● Cambium is present

● The number of xylem and phloem are two to four and they are

distinguished by a layer of parenchymatous cells called

conjunctive tissue.

● Vascular bundles in the stem are fewer and arranged in circles

or rings

● Pith is evident as is made up of palisade cells

● Bundle sheath absent around vascular bundles

● Pericycle is present

● Phloem parenchyma and phloem fibres are present

Leaves

● They have reticulate or net venation

● Leaves have a stalk

● The mesophyll that contains chloroplasts is composed of

spongy and parenchymatous cells

Flowers and seeds

● Flowers are usually pentamerous i.e the floral parts are present

in numbers of five

● Seeds germination either hypogeal or epigeal.

● They have two cotyledons

● The pollen grains have three furrows or pores.

Examples of dicotyledonous plants: Tomatoes, Cauliflower, beans,

apples, potatoes, etc

Monocotyledonous Plants

Roots

● They have an adventitious root system

● Pith is large and conspicuous

● The number of xylems is 6 or more

● Secondary growth is absent in monocots due to an absence of

cambium

Stem

● No cambium and so no secondary growth in stem

● Stem usually hollow

● Vascular bundles in the stem are scattered and numerous

● Phloem parenchyma is absent

● Pith is absent

● Vascular bundles are surrounded by a sclerenchymatous bundle

sheath

● Pericycle is absent

Leaves

● The leaves are sessile i.e it is directly attached to its base

(without stalk)

● They have parallel venation

● Mesophyll is not differentiated into spongy and palisade cells

Flowers and seeds

● Seed germination is hypogeal

● They have a single cotyledon

● Flowers are incomplete and trimerous(floral parts are in the

number of threes)

● The pollen grains have a single furrow or pore

Examples of monocotyledonous (monocot) plants: Maize, Corn,

Grass, Wheat

Understanding the anatomy of these plants is useful from the

horticultural and agricultural aspects. Choosing the right product for

the right kind of plant is important. A herbicide or pesticide designed

for a monocot might not help kill pests around a dicot. Due to the tap

root system that is found in dicots, they can penetrate deeper into the

soil compared to monocots who have a fibrous root system which

cannot penetrate that deep.

Learn more about the concept of Tissue System here in detail.

Solved Example for You

Q: Which of the following are features of dicot plants

(a) Taproot system (b) Fibrous root system

(c) Two cotyledons (d) both a and c

Sol. (d) both a and c

Dicot plants have a taproot system, and seeds contain two cotyledons.

The fibrous root system is found in monocots. So, the correct answer

is (d) both a and c