Morphology of Flowering Plants Revision Notes, Key Concepts & Important Questions

Morphology of Flowering Plants chapter explains the external structure and organisation of plants. It covers the morphology and functions of major plant parts such as roots, stems, leaves, inflorescences, flowers, fruits, and seeds. The chapter also discusses different types of root and shoot systems, modifications of plant organs, leaf arrangements, floral structures, and fruit types, helping students understand the form and structure of flowering plants.

ALLEN’s expert faculty has prepared these revision notes on the Morphology of Flowering Plants to provide a clear overview of key concepts, important terms, and structural features of plant organs. They are designed for quick revision, and help students strengthen conceptual clarity, remember important classifications and examples, and prepare effectively for board and competitive exams.

1.0Concept-Wise Important Revision Notes

1. What are flowering plants?

Ans: Flowering plants, also known as angiosperms, are the most diverse group of land plants. They are found in a wide variety of habitats on land, in freshwater, and even in marine environments. In flowering plants, the underground part forms the root system, while the above-ground portion forms the shoot system.

2. What is root? What are its types?

Ans: The root is the underground part of a plant that usually develops from the radicle of the seed. It lacks nodes and internodes and is generally non-green and subterranean. Roots typically show positive geotropism (grow towards gravity) and negative phototropism (grow away from light).

Types of Root Systems: There are three main types of root systems:

• Tap Root System: In many dicotyledonous plants, the radicle elongates to form the primary root, which gives rise to secondary and tertiary lateral roots. The primary root and its branches together form the tap root system. Example: Mustard.
• Fibrous Root System: Common in monocotyledonous plants, the primary root is short-lived and is replaced by numerous roots arising from the base of the stem, forming a fibrous network. Example: Wheat.
• Adventitious Root System: In some plants, roots arise from plant parts other than the radicle, such as stems or leaves. These are called adventitious roots. Examples: Grass, Monstera, Banyan tree.

3. What are the different regions of the root? Name the modification of roots.

Ans: Regions of Root: The root has four main regions:

• Root Cap: Protects the root apex while it penetrates the soil.
• Meristematic Region: Located just above the root cap, where cells actively divide.
• Elongation Region: Cells elongate in this region, helping the root grow in length.
• Maturation Region: Cells differentiate and mature; root hairs develop here to absorb water and minerals.

Modifications of Roots: Roots are modified to perform special functions:

1. Modified Roots for Support

• Prop Roots: Hanging roots that provide support (e.g., Banyan tree).
• Stilt Roots: Roots emerging from lower stem nodes for support (e.g., Maize, Sugarcane).

2. Modified Roots for Storage of Food

• Tap Roots: Become swollen to store food (e.g., Carrot, Turnip).
• Adventitious Roots: Swollen roots storing food (e.g., Sweet potato).

3. Modified Roots for Respiration

• Pneumatophores: Roots growing upward above the ground to obtain oxygen in swampy areas (e.g., Rhizophora).

4. What is stem? Explain their functions and modifications.

Ans: The stem is the ascending part of the plant axis that bears branches, leaves, flowers, and fruits. It develops from the plumule of the embryo of a germinating seed. The stem has nodes (points where leaves arise) and internodes (the regions between two nodes). It also bears terminal and axillary buds. The stem is usually green when young, later becoming woody and dark brown, and it shows negative geotropism.

Functions of Stem

• Spreads out branches bearing leaves, flowers, and fruits.
• Conducts water, minerals, and photosynthates throughout the plant.
• In some plants, stems also help in storage of food, support, protection, and vegetative propagation.

2.0Modifications of Stem

Stems are modified in different plants to perform special functions such as storage, vegetative propagation, climbing, protection, and photosynthesis.

Underground Modifications

• Tuber: Swollen underground stem that stores food. Example: Potato.
• Rhizome: Horizontal underground stem used for storage and perennation. Example: Ginger.
• Corm: Short, condensed, vertical underground stem. Example: Colocasia.
• Bulb: Reduced stem that stores food. Example: Onion.

Sub-Aerial Modifications

• Runner/Stolon: Horizontal stems that spread on the ground and form new plants. Example: Strawberry, Jasmine.
• Sucker: Stem that emerges above ground from underground parts. Example: Mint, Banana.
• Offset: Short runner in aquatic plants with leaves and roots. Example: Pistia.

Aerial Modifications

• Tendril: Modified stem used for climbing. Example: Grapes.
• Thorn: Modified stem that provides protection. Example: Bougainvillea.
• Phylloclade: Green stem that performs photosynthesis. Example: Opuntia.

5. What is leaf? Explain the modifications of the leaf.

The leaf is an important vegetative organ that arises laterally from the stem at nodes and is usually flattened to carry out photosynthesis. Leaves develop from the shoot apical meristem and are arranged in an acropetal order. 

A typical leaf has three main parts: 

• leaf base (hypopodium), which attaches the leaf to the stem
• petiole (mesopodium), the stalk connecting the lamina to the stem 
• lamina (epipodium), the broad green part responsible for photosynthesis and transpiration.

Modifications of Leaf

Leaves may be modified to perform functions other than photosynthesis:

• Leaf Tendril: Leaf or part of it becomes a thin, coiling structure for climbing. Example: Wild pea (Lathyrus aphaca).
• Leaf Spine: Leaves transform into sharp spines for protection. Examples: Opuntia, Cacti.
• Leaf Pitcher: Leaves form pitcher-like structures to trap insects or store water. Examples: Nepenthes, Dischidia.
• Leaf Bladder: Leaves develop bladder-like structures to trap small organisms. Example: Utricularia.
• Phyllode: Petiole becomes flattened and performs photosynthesis. Examples: Australian acacia, Parkinsonia.
• Leaflet Tendril: A leaflet modifies into a tendril for support. Examples: Garden pea (Pisum sativum), Sweet pea (Lathyrus odoratus).

6. Give a short note on

a. Flower

b. Fruits

c. Seed

ANS:

a. Flower: A flower is a modified shoot where in the shoot apical meristem changes to floral meristem. Internodes do not elongate and the axis gets condensed. When a shoot tip transforms into a flower, it is always solitary. Generally flowers have a short or long stalk which is called pedicel. The upper part of the pedicel is swollen, which is called thalamus. Floral leaves are present on it.

There are 4 types of floral leaves.

• Calyx (whorl of Sepals) 
• Corolla (whorl of  Petals)
• Androecium (whorl of Stamens)
• Gynoecium (whorl of pistils or carpels) 

b. Fruits: The fruit is the characteristic feature of the flowering plants. It is the mature or ripened ovary, developed after fertilisation.

• If a fruit is formed without fertilisation of the ovary, it is called a parthenocarpic fruit. 
• In some fruits like grapes, banana seeds are not found and such types of fruits are called parthenocarpic or seedless fruits. 
• Parthenocarpy can be induced through the application of growth hormones. Generally the ovary wall changes into pericarp. 
• This pericarp may be thick and fleshy or thick and hard or thin and soft.

In fleshy fruits pericarp (fruit wall) is made up of 3 layers :-

Outermost layer      = Epicarp

Middle layer            = Mesocarp

Innermost layer       = Endocarp

c. Seeds: The ovules after fertilisation, develop into seeds. A seed is made up of a seed coat and an embryo. The embryo is made up of a radicle, an embryonal axis and one (as in wheat, maize) or two cotyledons (as in gram and pea).

Types of Seeds

Based on Cotyledon Number

Monocotyledonous Seeds (Monocots)

• Have one cotyledon (seed leaf).
• Examples include grains like wheat, rice, and corn.

Dicotyledonous Seeds (Dicots)

• Contain two cotyledons.
• Examples include beans, peas, and almonds.

Based on Endosperm Presence

Endospermic Seeds (Albuminous Seeds)

• Retain endosperm at maturity, providing nutrition to the germinating seed.
• Examples: Most monocots, such as wheat and corn, and some dicots like castor.

Non-Endospermic Seeds (Exalbuminous Seeds)

• Consume the endosperm during development, and the cotyledons provide nutrition to the germinating seed.
• Examples: Most dicots, such as peas and beans.

3.0Memory Tricks

The mnemonics below help students remember important concepts from the chapter Morphology of Flowering Plants:

1. Parts of a Flowering Plant: “Real Students Love Fresh Food”

R → Root
S → Stem
L → Leaves
F → Flower
F → Fruit

2. Regions of the Root: “Cool Monkeys Eat Mangoes”

C → Cap
M → Meristematic region
E → Elongation region
M → Maturation region

3. Stem Modifications: “USA Stems”

U → Underground (Potato, Ginger, Onion)
S → Sub-aerial (Runner, Sucker, Offset)
A → Aerial (Tendril, Thorn, Phylloclade)

4. Floral Whorls: “Cute People Always Glow”

C → Calyx
P → Corolla
A → Androecium
G → Gynoecium

Also Read:

• Corolla of a Flower
• Sexual Reproduction in Flowering Plants

4.0Previous Year Questions on Morphology of Flowering Plants