Consider the following Flora:
1. Congress grass
2. Water hyacinth
3. Nilakurinji
Which among the above is / are invasive species?

Answer: [A] Only 1 & 2

The Congress Grass (Parthenium hysterophorus) inhibits the germination and growth of many plants and induces hay fever, asthma, skin rashes, and eczema in human beings.  Toxic to animals, it can also taint mutton and make dairy milk unpalatable owing to its odour.

Water hyacinth (Eichhornia crassipes):

Aquatic plant of tropical South America that flourishes in warm climates in Central America, North America, Africa, Asia, Australia and New Zealand. The hyacinth grows in thick rafts, deoxygenating the water for other species and impeding water flow and navigation.

This question is a part of GKToday's Integrated IAS General Studies Module