Question

What are the weeds? How can we control them?

Answer 1

Hint: Common examples of weeds seen in India include Dandelion, carrot grass (Parthenium hysterophorus), Indian lantana (Lantana camara), milkweed. Weeds need to be kept in check or they end up harming the useful plants.

Complete answer:
Weeds are undesirable plants that grow in human-controlled settings such as farm fields, gardens, lawns, and parks along with useful crops. Weeds compete with useful crops for nutrients and thus hinder their growth. The process of controlling or removing weeds is known as weeding which can be achieved through physical means, chemical means, etc.
-Chemicals mean using weedicides that are sprayed in the fields which kill the weeds but not the crops.
-Tilling or plowing the soil before sowing seeds results in the uprooting of the weeds.
-Weeds can be removed manually by a person who uproots the weeds individually.

Additional Information:
Carrot grass: It is a species of flowering plants in the Aster family which is an invasive species in India, Australia, and parts of Africa. This plant produces allelopathic chemicals that do not allow plants to grow near it. Common names of Parthenium include gajar ghas, congress ghas, etc. The pollen grains of Parthenium are responsible for causing pollen allergies such as asthma, bronchitis, etc.
Indian lantana: It is a species of flowering plants in the verbena family that is commonly known as big-sage in Malaysia, Gu phool in Assam, etc. It is native to Central and South America and was brought to India by the Portuguese. This weed has the ability to form dense thickets which, if not controlled reduces the productivity of farmland.

Note: -An invasive species is said to be a species that is present in a non-native location and spreads very rapidly due to a lack of natural predators.
-The effects of an invasive species are so negative on the ecosystem that is one of the major reasons for biodiversity loss.
-One such example of invasive species is the water hyacinth which is known as ‘The Terror of Bengal’ due to its disastrous effects on the ecosystem of Bengal.
-Parthenium was introduced in India as a contaminant along with imported wheat.