DIVERSITY OF FLOWERS

Parts of flowers

Arrangement of flowers

1.Calyx

Calyx is a cup shaped structure. It is found at the bottom of all the other parts. It consist

of sepals. Sepals are similar to small green leaves. Colourful sepals can be in some flowers. Function of the calyx is the protection of tender the

flower bud.Photosynthesis takes place in green in coloured sepalsColourful sepals are important to attract insects for

pollination

Rose

Musandas

Musandas Muntingia

Sesbenia Tribulus

Image for calyx flowers

2.Corolla

Within the calyx are the whorl of floral leaves called petals, together and forming the corolla.

It is the most beautiful and attractive part of the flower.

The corolla protects the internal parts of flower and also helps to attract insects for pollination.

The corolla is colourful in majority of flowers which are pollinated by insects

Corolla shows diversity in colour and shape

Clitoria

AlstoniaCatharnthusOrchid

WrightiaShoe flower

Image for corolla flowers

In most of the flowers which bloom during the night, the corolla is white in colour and the flowers are scented.

This is also important to attract insects for pollination

Coral jasmine Getapichcha Kadupul

3.Androecium

Androecium is the male part of a flower. It is the whorl of floral leaves found inside

the corolla.Androecium consists of stamens.A stamen consists of the another and the

filament.The function of the androecium is to produce

and release pollen grains.Stamens of flowers can be independent or

connected to the petals.

Brassica

CalotropisPassion fruitGloriosa

TorneiaShoe flower

Image for androecium flowers

4.Gynoecium or pistil

Gynoecium or pistil is the female part of a flower.

It is the innermost part of a flower .It consists of three parts namely

stigma, style, and ovary.The stigma is situated at the top and

the ovary is situated at the base.The style is a tube like structure which

connects the stigma and the ovary.Ovules can be seen in the ovary.After pollination the ovary becomes

the fruit and the ovules become seeds.

5.Bisexual flowers

If the both gynoecium (pistil) and the androecium are present in a flower it is called a bisexual flower.

Examples for bisexual flowers.

Shoe flower Sesbenia Casealpinia

Blue lily

6. Unisexual flowers

In some flowers only one of these two parts are present. Such flowers are called unisexual flower.

Examples for unisexual flowers.

Coconut flowers

Symmetry of flowers

If a flower can be divided into two similar halves by cutting vertically through any one of its axis which passes through the centre, such flowers are known as radially symmetrical flowers or an actinomorphic flowers.

1. Radially symmetrical flowers or an actinomorphic flowers.

Image for Actinomorphic flowers

Shoe flower WrightiaTemple flower

Catharnthus KaduruPumpkin

2. Zygomorphic flowers

Some flowers can be divided into two similar halves by cutting along only one symmetrical axis.

These flowers can be known as bilaterally symmetrical flowers or zygomorphic flowers.

Image for Zygomorphic flowers

Salvia

Sesbenia CaesalpiniaThunbergia

CrotolariaLeucus zeylaniea

3. Asymmetrical flowers

Some flowers cannot be divided into two similar halves by cutting along any axis.

These flowers are known as irregular or asymmetrical flowers.

Examples for such flowers.

Species of cactusSpecies of cactus

Species of cactus

Species of cactus

Structure of flowers

There are some standard methods to describe the structure of flowers.

They areWhole flowerHalf flowerFloral diagram

1. Whole flower

By observing a flower externally we can study structure of the flower.

To observe the colour, nature, its parts and their position in the flower by the naked eye one has to observe a whole flower

1. Half flower

To observe the parts of a flower more clearly we can separate a flower into two similar halves through a symmetrical axis of the flower

Because some parts which cannot be seen by observing the flower externally clearly seen in a half flower.

Therefore a half flower is used to describe the structure of a flower.

Half flower can be depicted by a line.

3. Floral diagram

A transverse section drawn so that all the parts of the flower are in the same level is called a floral diagram.

This is similar to a diagram of a flower drawn as seen from the top.

To draw a floral diagram the main axis of the tree should placed the anterior side and the bract should placed to the posterior side.

Position of a flower in the treeFloral diagram of flower

1) If the both gynoecium and androecium are present in a flower it is known as

Corolla of the flowers

Unisexual flowers

Calyx of the flowers

Bisexual flowers

2)If a flower can be divided into two similar halves by cutting vertically through any one of its axis which passes through the center such flowers are known as

Androecium

Zygomorphic flowers

Actinomorphic flowers

Asymmetrical flowers

3)Example for asymmetrical flower is

Orchid

Sesbenia

Cactus

Rose

4)Example for actinomorphic flower is

Pumpkin

Cannon ball tree

Coconut flower

Lotus

3)Example for zygomorphic flower is

Caesalpinia

Shoe flower

Passion fruit flower

Gloriosa

U.VinusanJaffna Hindu College

Grade 9

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