do the same thing for flower structure and

function
Below are outstanding, comprehensive notes for ICSE Class 9 Biology – Chapter: The Flower
(Structure and Function), styled like the Selina textbook and ready for direct use in Word.
Copy and paste this into your Word document for a complete, exam-ready resource.

ICSE Class 9 Biology

Chapter: The Flower (Structure and Function)

1. Definition and Importance

Flower: A flower is a specialized shoot in which the leaves are modified into floral structures.
It is the reproductive unit of angiosperms, meant for sexual reproduction [1] [2] .
Inflorescence: The mode of arrangement of flowers on the axis of a plant [1] .
Significance: Flowers ensure the continuity of plant species through sexual reproduction.

2. Parts of a Typical Flower

A typical flower consists of four main whorls arranged on a swollen tip of the flower stalk
(thalamus):

Whorl Name Members Essential/Accessory Main Function(s)

Calyx Sepals Accessory Protects bud, sometimes photosynthesis

Corolla Petals Accessory Attracts pollinators, protects inner whorls

Androecium Stamens Essential Male reproductive organ (produces pollen)

Gynoecium Carpels/Pistil Essential Female reproductive organ (produces ovules)

3. Detailed Structure and Functions

A. Calyx (Sepals)
Description: Outermost whorl, usually green and leaf-like.
Types:
Gamosepalous (sepals united)
Polysepalous (sepals free)
Functions:
 Protects the flower in the bud stage.
May photosynthesize [2] .
Sometimes attracts pollinators if brightly colored.

B. Corolla (Petals)
Description: Second whorl, often brightly colored and scented.
Types:
Polypetalous (petals free)
Gamopetalous (petals fused)
Functions:
Attracts pollinators (insects, birds) by color, scent, and nectar.
Protects reproductive whorls [2] [3] .
May have nectaries at the base for nectar secretion, aiding pollination [3] .

C. Androecium (Stamens)
Description: Third whorl, male reproductive part; consists of stamens.
Each Stamen Has:
Filament: Stalk that holds the anther.
Anther: Bilobed, contains pollen sacs with pollen grains (male gametes) [1] [2] [3] .
Connective: Joins the two lobes of the anther.
Functions:
Produces and releases pollen grains for fertilization [1] [2] [3] .
Filament positions anther for effective pollen transfer.

D. Gynoecium (Carpels/Pistil)
Description: Innermost whorl, female reproductive part; made of one or more carpels.
Each Carpel Consists of:
Stigma: Sticky, terminal part; receives pollen [1] .
Style: Slender stalk connecting stigma to ovary.
Ovary: Swollen base containing ovules.
Ovule: Contains the female gamete (egg cell).
Placenta: Swollen region in ovary where ovules attach [1] .
Functions:
Stigma receives pollen during pollination.
Ovary develops into fruit after fertilization.
 Ovules develop into seeds.

4. Accessory Structures
Thalamus (Receptacle): Swollen tip of the flower stalk bearing all floral whorls [1] .
Bract: Leaf-like structure at the base of the flower stalk [1] .
Epicalyx: Additional whorl outside the calyx in some flowers [1] .

5. Types of Flowers
Type Description

Complete Has all four whorls (calyx, corolla, androecium, gynoecium) [3] .

Incomplete Lacks one or more whorls.

Bisexual Has both stamens and carpels (e.g., hibiscus) [4] [3] .

Unisexual Has either stamens or carpels, not both (e.g., papaya, cucumber).

Regular (Actinomorphic) Symmetrical along multiple planes (e.g., mustard).

Irregular (Zygomorphic) Symmetrical along only one plane (e.g., pea).

6. Functions of a Flower
Site of sexual reproduction in angiosperms.
Produces male and female gametes.
Facilitates pollination (transfer of pollen).
Ensures fertilization and formation of seeds and fruits.
Attracts pollinators via color, scent, and nectar [5] [3] .

7. Placentation
Definition: Arrangement of ovules within the ovary [1] .
Types: Marginal, axile, parietal, basal, free central (not detailed here, but should be known).

8. Diagram Practice
Labelled diagram of a typical bisexual flower:
Show and label: Pedicel, thalamus, calyx, corolla, androecium (filament, anther),
gynoecium (stigma, style, ovary, ovule), bract (if present).

9. Key Terms (Definitions)

Flower: Specialized shoot for sexual reproduction.
Inflorescence: Arrangement of flowers on a plant.
Bract: Leaf-like structure at the flower base.
 Epicalyx: Additional whorl outside the calyx.
Placenta: Region in ovary where ovules attach.
Stigma: Sticky tip of pistil for pollen reception.
Thalamus: Swollen tip of flower stalk bearing whorls.

10. Review Table: Whorls and Their Functions

Whorl Members Main Function(s)

Calyx Sepals Protects bud, sometimes photosynthesis

Corolla Petals Attracts pollinators, protects inner whorls

Androecium Stamens Produces pollen (male gametes)

Gynoecium Carpels Produces ovules (female gametes), forms fruit

11. Practice Questions

1. Draw and label a typical bisexual flower.
2. Differentiate between calyx and corolla.
3. State the functions of the following: stigma, anther, thalamus, placenta.
4. What is placentation? Name its types.
5. Why are petals often brightly colored?
6. What is the function of sepals in a flower bud?
[End of Notes]
Instructions:
Paste this content into your Word document.
Use "Insert Table" for tables if you want improved formatting.
Add diagrams by hand or insert images as needed.
If you want more detail on any section (e.g., types of placentation, more on pollination, or extra
diagrams), let me know!
⁂

1. https://www.knowledgeboat.com/learn/class-9-icse-concise-biology-selina/solutions/v85My/flower
2. https://www.aplustopper.com/frank-icse-solutions-class-9-biology-flowers/
3. https://www.youtube.com/watch?v=GGJbbBCoLK4
4. https://www.youtube.com/watch?v=2re3AJEq0Qs
5. https://krishnagaracademy.in/wp-content/uploads/2020/06/Class-IX-Biology-The-Flower.pdf