Question

What is the difference between flora, fauna and vegetation? Eichhornia crassipes is an exotic species while Rauwolfia serpentina is an endemic species in India. What do these terms exotic and endemic refer to?

Answer 1

Hint: The first question is related to a group of organisms when referred as a whole. They have some decent differences that will be discussed soon.
The second question is related to the ‘place of origin of species’, like, whether a species is from the same ecosystem or has been introduced into it from outside.

Complete answer:
The term flora refers to the total plant species found in a specific area or ecosystem.
The term fauna refers to the diversified animal population of a specific area or ecosystem.
The term vegetation is yet another term that signifies the overall plant diversity of a large area (larger than an ecosystem) like a part of a city or country. For example, the African savannah region has grassland type of vegetation.
Now we come to the second question.
EXOTIC SPECIES: When new species from another geographical area or ecosystem enter into another one, then that particular species is termed as exotic species or alien species.
These exotic species, whether introduced intentionally or unintentionally, may cause extinction of the local species of the ecosystem.
Water hyacinth or Eichhornia crassipes was introduced into Bengal in India by the Europeans. The common predator of water hyacinth in India is absent. And due to its fast vegetative reproductive modes, the plant soon clogged the water bodies at many places and resulted in the death of many aquatic flora and fauna.
ENDEMIC SPECIES: These are the species that are found in a particular ecosystem only. By the word particular ecosystem, we mean that the species is not found in any other place in the world. Some species of the western ghats are found only there, and not in any other place. E.g., Rauwolfia serpentina.

Note:
One thing to note about exotic species is that they are one of the most probable causes of biodiversity losses. In fact, it falls under the four major causes accounting to biodiversity threat and is collectively termed as “The Evil Quartet”. The four causes are Habitat loss and fragmentation, over-exploitation, Alien species invasion, Co-extinctions.
The endemic species are found only in specific areas and they have a key role in the ecosystem. It means that their role in that ecosystem is much higher than the commonly found other species.