Structural Organisation in Plants

All living things are made up of cells. Cells are the basic units of life. In plants and animals, many cells work together. These cells group to form tissues in the body.

Organs are made of tissues. In plants, the leaf is an organ; in animals, the heart is an organ. Organs work together to form systems in the organism. Each level helps the body perform important life functions well.

Structural Organisation in Plants

Plants have a simple but useful structure. Their body has roots, stems, leaves, flowers, fruits, and seeds. Plant tissues are of two main types: meristematic and permanent tissues.

Meristematic Tissue

Meristematic tissues are found in growing areas of the plant. They help the plant grow by forming new cells. These tissues are found at the root and shoot tips (apical meristem).

Intercalary meristem is present at the base of nodes and internodes (e.g., grasses), not strictly between nodes.

Permanent Tissue

Permanent tissues are formed from meristematic tissues. These cells do not divide. They are of two types:

Simple and Complex

Simple permanent tissues include parenchyma, collenchyma, and sclerenchyma.
Complex permanent tissues include xylem and phloem.

Xylem carries water and minerals from roots to other parts. Phloem moves food from leaves to the rest of the plant.

Morphology of Flowering Plants

Morphology means the study of outside features. Flowering plants are called angiosperms. They have roots, stems, leaves, flowers, and fruits. These parts help plants grow and reproduce.

Root System

Roots fix the plant in the soil. They also absorb water and minerals.

Tap root system - Found in dicots like mustard. One main root grows deep.
Fibrous root system - Found in monocots like wheat. Thin roots grow from the stem base.
Adventitious roots - Arise from parts other than the radicle (like stems or leaves). Found in banyan (prop roots) and grass (fibrous roots).

Stem

The stem bears branches, leaves, flowers, and fruits. It has nodes and internodes (gaps between nodes). The stem supports the plant and carries water, minerals, and food.

Leaf

Leaves grow at the nodes. A typical leaf has three parts: the leaf base, the petiole, and the lamina. Leaves help in making food through photosynthesis.

Phyllotaxy - It is the arrangement of leaves on the stem.

Alternate - One leaf at each node (mustard, sunflower).

Opposite - Two leaves at a node (guava, Calotropis).

Whorled - More than two leaves at a node (Alstonia).

Inflorescence

It is the arrangement of flowers on the floral axis (peduncle).

Flower

A flower is a modified shoot. It helps in reproduction. The shoot tip becomes a floral meristem. Flowers may be solitary or in groups.

Fruit

Fruits are formed after fertilisation. A fruit has seeds and a pericarp (fruit wall). The pericarp can be dry or fleshy. Fleshy fruits have epicarp, mesocarp, and endocarp.

Anatomy of Flowering Plants

Anatomy is the study of internal structure. Different plant parts have different internal designs.

Epidermal Tissue System

Epidermis - The outer layer. It protects the plant.
Cuticle - A waxy layer that prevents water loss.
Stomata - Openings for gas exchange. Guard cells control them.

Ground Tissue System

It includes parenchyma, collenchyma, and sclerenchyma. These tissues support the plant and store food. In leaves, the ground tissue is called the mesophyll.

Vascular Tissue System

It includes xylem and phloem. These help in the movement of water, minerals, and food.

Dicot and Monocot Anatomy

Dicot Root

Some dicot roots show secondary growth.

Tissues include epidermis, cortex, pericycle, vascular bundles, and pith.

Monocot Root

It looks like a dicot root but has more xylem bundles (polyarch). The pith is large and there is no secondary growth. Some monocots like palms show anomalous secondary growth.

Dicot Stem

It has vascular bundles in a ring. It can undergo secondary growth due to cambium.

Monocot Stem

Vascular bundles are closed (no cambium). Surrounded by sclerenchymatous bundle sheaths. No secondary growth.

Summary

Plants have simple structures made of many cells and tissues. Meristematic tissues help plants grow by making new cells. Permanent tissues support the plant and carry food and water.

Roots, stems, and leaves all have key roles to perform. Inside plants, there are systems for protection, support, and transport. Dicots and monocots have different root and stem patterns.

FAQs

Q1. What are the main types of plant tissues?

A. Plant tissues are of two main types:

Meristematic
Permanent

Q2. What are simple permanent tissues?

A. Simple permanent tissues are made of a single type of cell. They include parenchyma, collenchyma, and sclerenchyma. These give support, storage, and flexibility.

Q3. What are the main parts of a flowering plant?

A. The main parts are