Yes, MANGROVES is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, N 1, G 2, R 1, O 1, V 4, E 1, S 1.

Is it a valid word?

MANGROVES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a tropical tree or shrub bearing fruit that germinates while still on the tree and having numerous prop roots that eventually form an impenetrable mass and are important in land building

Also: rhizophora mangle.