A very beautiful place with thousand of different species.
If you travel to Singapore Botanical Gardens, go there early in the morning, when it is not so crowded.
Entrance fee is about 10 SG$ (7-8 US$) and absolutely worth to spend 1-2 hours there. There are also beautiful walkways around on the Botanical Garden (no entrance fee).
If you are looking for the traditional nature of Asia and Singapore, this place will be perfect. If you prefer more the modern style with supertrees and show - go to the Gardens by the Bay (opposite Marina Bay Sands Hotel and Casino).