1)In current times, they are becoming key players in both the conservation of plants and in the education of the people who come to see them. 
2)They are playing a role in the mitigation of the effects of climate change, and could be absolutely vital to the survival of the planet as they are perfectly placed to help move species around and help ecosystems to adapt to new climates in different regions.
Botanic gardens play a key role in the conservation of the world's plant diversity and the education of people in environmental issues.
1) it helps in restoring ecosystem
2)  Botanical garden raise general awareness among people in keeping the greenery alive.
3) It is also a source of scenic beauty
4) It not only helps in conservation of plants but also educates the people about species of plants
5) Plants get proper climatic conditions in this gardens which is very useful.