1) A woody tree or shrub that grows in tidal estuaries, characterized by its indiscriminate rooting system
2) A guy who has both a high libido and fairly low standards when it comes to women, particularly when drunk. Typically, a man who has a lot of sex, but doesn't really differentiate who with.
i.e, Also an indiscriminate rooting system.
Pass Mike another beer, we need a mangrove to fall on that grenade dancing with those hotties.