plants:
it is basically shrubs and small acacias that are adapted to hyperaridity
Palm trees would grow only in places with permanent groundwater
From my POV, Your water pool is more the kind of shallow depression that collects water after rainy episodes - However I don't know what You intended
Vegetation would be not very greenish, only when very close to water, but You can strew in the occasional small shrub everywhere
Someone here in the forum (I think it was Captain Blood) made removable vegetation on needle pins that can be stuck into the Styrofoam