Plants: Classification, Flower Parts, Photosynthesis, Pollination

Classification Of Plants:

Plants are those organisms that contain chlorophyll and synthesize their own food through photosynthesis. Plants are divided into:

1) Flowering Plants OR Phanerogams

2) Non-Flowering Plants OR Cryptogams

Flowering Plants

Flowering plants or Phanerogams contain seeds. They are further subdivided into:

i) Gymnosperms

ii) Angiosperms

Gymnosperms:

Gymnosperms are those flowering plants that contain naked and unprotected seeds.

Examples: Pine, Fir, Cedar, Spruce and Cypress, etc.

Angiosperms:

Angiosperms are those flowering plants whose seeds are protected by a fruit or seed pod.

Examples: Grass, Crops, Vegetables, Fruits, and weeds.

Non-Flowering Plants or Cryptogams

These are the plants that do not have a seed or in other words, they are seedless. Following are the main characteristics of cryptogams:

– They reproduce by spores

– They have a long life

– They have no long fibers

– They cannot grow to greater size

– They generally have a simple structure, except for ferns.

Examples: Moses, Ferns, Algae.

Flower & Its Parts

The flower is the reproductive part of the plant. It is mainly concerned with the formation of seeds. It is regarded as a modified shoot for the purpose of reproduction.

Parts Of Flower

A typical flower consists of a short axis known as the thalamus, on which floral leaves are inserted in four distinct whorls, which are as under:

i) Calyx

ii) Corolla

iii) Androecium

iv) Gynaecium

Calyx:

The calyx is the outermost whorl of floral leaves called sepals. The sepals can be defined as green and leaf-like structures that are mainly concerned with the protective function.

Corolla:

Corolla is the second whorl of floral leaves called petals. The petals are beautifully colored which are responsible for the attraction to the insects towards them.

Androecium:

The third whorl of the leaves consists of stamens. It is considered the male part of the flower.

Gynaecium:

Gynaecium is the innermost whorl of the floral leaves called carpels. It is considered the female part of the flower.

Photosynthesis

Definition:

Photosynthesis is a process in which plants manufacture their food (simple carbohydrates) in the presence of chlorophyll and sunlight by the combination of carbon dioxide and water.

Raw Material For Photosynthesis:

i) Carbon dioxide: Taken from the air

ii) Water: Absorbed by roots from the soil

iii) Sunlight: From Sun

iv) Chlorophyll: green pigment present in leaves

By-Products Of Photosynthesis:

i) Carbohydrates (simple sugar): used by plants as a food material and excess of it is converted into starch

ii) Oxygen: Released into air

Importance Of Photosynthesis:

i) Major process of food production in plants

ii) Utilization of CO2 of the atmosphere and liberation of oxygen

iii) Important in reducing CO2 of the atmosphere which is dangerous for the human beings as well as animal health.

Pollination

Definition:

Pollination is the phenomenon of transfer of pollen from the male reproductive organs (anther) to female reproductive organs (stigma) in flowering plants through a biological or physical agency.

Types Of pollination:

There are two types of Pollination

i) Self-Pollination:

In this type of pollination, pollens are transferred to the stigma in the same flower. Some plants are by nature self-pollinated as wheat and grasses.

ii) Cross-Pollination:

In this type, the pollen grains are transferred from the anther of one flower to the stigma of another flower. Cross-pollination is considered and advantageous to the plant as the seeds produced by cross-pollination are usually greater in number and the plant germinated from them is superior in vigor, height and weight.

Vehicles For Pollination:

Vehicles for pollination are animals, water, wind, and insects. Therefore cross-pollination may be:

a) Entomophily-by insects

b) Anemophily-by wind

c) Hydrophily-by water

d) Zoophily-by animals

Importance Of Pollination:

• Vital process for reproduction in plants

• Reproduction is carried out by reproductory organs of plants due to pollination

• It is the process by which seeds are produced.

Also Read: General Science and Ability Notes and Mcqs