Sea Purslane

Habitat:

a native, herbaceous perennial found along the coasts of Florida. It grows on the ocean side of the dunes down to the high tide mark forming dense stands close to the ground.

Notes:

I would say this is the predominant plant feature of the Coastal Prairie in the extreme southern coast of the Everglades National Park. It forms a thigh high ground cover in vast numbers across these tidal/marshy fields.