Getting to Know Plants Class 6 Notes CBSE Science Chapter 7 [Free PDF Download]

Introduction:

A variety of plants are seen everywhere. Some of them are small or tall, with thick stems or tender stems, and with different types and colours of leaves, flowers, and fruits. But all these plants have the same common parts, which is root, stem, leaves, buds, flowers, and fruits, though they may be different in colour, size, or shape.

Classification of Plants:

• As the plants are different in their sizes or type of stems the similar type of plants can be classified into some groups based on these characteristics. They can be classified as follows:

1) Based on Size of the Plant and The Type of Stem:

The plants have different sizes and have different types of stems, it can be hard, tender, or soft. The different types are as follows:

a) Herbs: 

• These are the plants that have green tender stems and are usually short in size. 

• These are mostly the plants that provide us with herbs that are used in cooking and as medicines. 

• Examples - Tulsi, mint, mustard, wheat, etc.

b) Shrubs: 

• These plants have a hard stem and have small branches starting from the base of the plant. 

• They do not grow very big, but are bigger than herbs. 

• Example - Rose, sunflower, tea, etc.

c) Trees: 

• These are the biggest plants that have woody, hard stems with a lot of branches.

• Their wood is often used to make houses and furniture. 

• Example - Mango, neem, teak, etc.

d) Creepers: 

• These types of plants have very weak stems and are not able to stand up, so they spread and grow on the ground. 

• Example - Pumpkin, cucumber, etc.

e) Climbers: 

• These are again plants with weak stems but they climb onto something like a tree for support to grow. 

• Example - Money-plant, pea plant, etc.

2) Based on the Life Cycle of Plants:

The plants can be grouped on the basis of the time taken by them to complete their life cycle.

a) Annuals: 

• These are the plants that take one season to complete their life cycle. 

• Example - Wheat, rice, corn, etc.

b) Biennials: 

• These plants take two seasons for the completion of their life cycle. 

• Example - Carrots, onion, banana, etc.

c) Perennials: 

• These plants take more than two years to complete their life cycle and usually have a long lifespan. 

• Examples - Mango, apple, etc.

3) Based on Flowers:

The plants may have flowers or may not have them. So, they can be broadly grouped as:

a) Flowering Flants: 

• These are the plants that bear flowers. 

• Example - rose, jasmine, papaya, etc.

b) Non-Flowering Plants: 

• These plants do not bear flowers. 

• Example - Ferns, moss.

Parts of a Plant:

• A plant has mainly two parts, one that stays above the ground or soil, which is called the shoot system and the portion below the soil called the root system. 

• Many parts of the plants are edible, that is it can be eaten. Example - Leaves; spinach, cabbage, onion. Stem; celery. Flower; cauliflower, broccoli. Fruits; mango, banana. Seeds; pulses. Roots; carrots, radish.

Shoot System: 

This contains all the portions above the soil like stem, leaves, buds, flower, fruit.

1) Stem:

• The main part of the plant on which all the other parts are borne is called the stem. It bears the branches, leaves, buds, flowers, and fruit. 

• It keeps the plant in an upright position and provides support to the plant. 

• The main function of the stems is to transport the water and the minerals from the soil to different parts of the plant. 

• A simple experiment can be used to observe this. When a freshly cut stem of a plant is kept in a red coloured solution of water, and then it is seen that the red colour is seen in the stem, if it is cut and also in the leaves after some time. 

• Sometimes the stem is also modified to store food as in potato (underground) or to threadlike structures called tendrils for climbing.

2) Leaf: 

• The leaf is a structure that is attached to the stem of the plant and is generally green in colour. It may be of other colours too as in some ornamental plants. 

• The point by which the leaf is attached to the stem is called the petiole of the leaf. 

• The broader flat part of the leaf is called the lamina. 

• There are some lines on the leaf which are called veins. A central main line that is visible in the leaf is called the midrib. 

• The design made by the veins of the leaf are termed as leaf venation. This venation can be of two types:

a) Reticulate venation: This is a net like design formed by the veins on both the sides of the midrib. Example - mango leaf.

b) Parallel venation: In this type of venation the design of the veins are parallel to each other. Example - grass.

• The leaf has two main functions:

a) Transpiration: 

• This is the process by which the leaves lose water in the form of water droplets from the leaves, by evaporation.

• This maintains the balance of water in the plant for its survival. 

• This can be easily observed by tying a polythene cover on a leaf of a plant. Water droplets appear inside it after some time which shows that leaves lose water. 

b) Photosynthesis: 

• The other main function of the leaves is to make food for the plant. The green pigment in the leaves called chlorophyll in the presence of sunlight, carbon dioxide, and water, prepares food for the plant. 

• The oxygen is released in this process and the food is used and stored in the plant.

3) Buds:

The buds are basically a shoot that is in the stage of development. It appears as a small projection from the stem. 

4) Flowers:

• The flowers are the colourful part of the plant which are beautiful to look at. They may be scented also. It makes it easy to identify the plants by the colour and shape of the flowers, like roses and marigolds. 

• The main parts of a flower are as follows:

a) Sepals: 

• They are the outermost layer of small leaf-like structures of a flower. 

• They are mostly green in colour and their function is to protect the flower and give support to the petals.

b) Petals: 

• These are the coloured layer after sepals. They could be of various colours and shapes. Like roses and sunflowers possess distinct shapes and colours. 

• These are brightly coloured to attract insects and birds for pollination. They also protect the inner layers of the flower.

c) Stamen: 

• These are the male parts of the flowers. They are long thread-like in shape with a swollen portion at the end. These are also of different sizes and numbers. 

• Each stamen is made of a long thin tube called filament. 

• The swollen portion at the end of the filament is called another which carries the pollen grains.

d) Pistil: 

• It is the female part of the flower. They are usually present in the middle of the flower. It consists of three parts namely, stigma, style and ovary. It is attached to the plant by the pedicel.

• The sticky part at the top end of the pistil that receives the pollen grains is the stigma.

• It is connected to a long thin tube called the style which carries the pollen grains to the ovary. 

• The ovary is a swollen part at the end of the pistil that contains the ovules or the developing seeds.

 Root System: 

• It consists of the parts of the plants that are below the soil, that is roots. 

• The roots are very important for the plants as they absorb water and minerals from the soil. This is then transported to the different parts of the plants by the stem for preparing food and so it helps in the growth of the plant. 

• The roots also function as an anchor for the plant as it holds the plant firmly to the ground and lets it stand straight. 

• The roots also store food and these are edible. 

• The roots can be of two different types:

1) Tap Roots: 

• This type of root has one main or primary root that grows down into the ground. It has many small roots coming from it. 

• This root is firmer and more difficult to pull out as it holds strongly in the ground and goes deep into the soil. 

• They often store food in them and so are beneficial to humans. They can be of different shapes. 

• Example - roots of trees like mango, etc and others like turnips, carrots, etc.

2) Fibrous Roots: 

• This type of root does not have a main root and it has many roots that are almost of the same size. 

• They spread like a thread-like structure in the soil and so they don’t go deep into the soil. These can be easily pulled out. 

• Examples - onion, grass, etc.