6th chp 7 Notes

         Class 6th Science Notes       

      Chapter 7 Getting to know Plants      

From where does a plant come?

→ A plant comes from a seed.

→ This seed is covered with seed coats, which protect the seed.

→ This seed contain a baby plant inside, it has a tiny root towards the outer side.

→ The tiny root is termed as radicle.

→ It also has a tiny shoot towards the inner side.

→ The tiny shoot is termed as plumule.

Classification of plants on the growth habit

→ The plants are classified in five types based on growth habit:

(i) Herbs

(ii) Shrubs

(iii) Trees

(iv) Climbers

(v) Creepers

(i) Herbs

→ Have soft, green and weak stems. Usually its height is short and may not have many branches. It is used for food, flavouring, medicine or perfume.

→ Examples: rice, wheat, maize, sunflower, mint, etc.

(ii) Shrubs

→ They are bushy and have hard stems which do not bend easily. These plants have their stem branching out near the base.

→ Examples: lemon, China rose, jasmine, etc.

(iii) Trees

→ These are big plants which have strong and long stem. Live for many years.

Examples: mango, neem, banyan, coconut, etc.

(iv) Climbers

→ Plant that take support on neighbouring structures and climb up are called climbers. It has weak stems and cannot stand erect.

→ Examples: pea, grapes etc.

(v) Creepers

→ Plants which creep on the ground and spread out is called creepers. It has weak stems that cannot stand upright.

Example: pumpkin and watermelon.

Classification of Plants on the basis of life cycle

→ The Plants are classified in three types on the basis of life cycle:

(i) Annuals

(ii) Biennials

(iii) Perennials

(i) Annuals: Plants whose life cycle is completed in one season.

Examples: wheat and mustard.

(ii) Biennials: Plants whose life cycle requires two seasons for completion.

Example: carrot, radish and potato.

(iii) Perennials: Plants whose life cycle runs for more than two seasons.

Example: guava, babul and palm trees.

Parts of plants and their function

→ Plants are divided in 3 types based on their functions:

(i) Root System

(ii) Shoot System

(iii) Flowers

(i) Root system

→ The underground part of a plant is called root.

Types of root system:

(a) Tap root system

→ Primary root comes out from the seed after germination. It is also called true roots.

(b) Fibrous root system

→ These roots grow from the base of the stem have a bushy appearance. Fibrous roots are thin and almost equal in size.

Functions of roots

→ Help to anchor the plant firmly into the ground.

→ Root help plants to absorb water and nutrients from soil.

(ii) Shoot system

→ All parts of a plant that are above the ground form the shoot system.

Types of shoot system:

(a) Stem

→ It holds leaves in position and helps them to spread out as the stem and its branches grow.

→ It bears flowers, buds, leaves, and fruits.

(b) Leaf

→ A leaf is a flat and green structure on a plant, coming out from a node on the stem and always bearing a bud in its axil.

→ Parts of leaf are:

• Petiole

• Leaf lamina

• Veins

(iii) Flowers

→ A flower is the reproductive organ of a plant.

→ Flower gets developed into fruits and the fruits contain seeds with them for next generation.

Parts of flowers:

(i) Pedicle: Stalk of the flower through which the flower is joined to the branch.

(ii) Sepal: Small green leaf-like structure on the thalamus.

(iii) Petals: Petals attract the insects and help in the process of reproduction.

(iv) Stamens: These are male organs of the flower. It consists of two parts:

(a) Anther

(b) Filament

(v) Carpel: It is female organ of the flower. It consists of three parts:

(a) Style  (b) Stigma  (c) Ovary