Ruppia maritima flower
Pliocene
Rita Blanca Formation
Oldham County, TX USA.

32mm widgeon grass flower on 50mm slab. Only one we have ever seen.

Ruppia is a genus of aquatic plants commonly known as widgeonweeds, widgeon grasses, or ditch grasses.  It dates back to the Eocene

Today, R. maritima is commonly called the beaked tasselweed or widgeon grass.  It is found all over the world in brackish water environments.