Psammophyte. This seems to be a fancy way of saying seaweed. Since this word is too hifalutin’ for the American Heritage or even Merriam-Webster teams to take on, here’s a definition of the term from Dawes and Mathieson (Seaweeds of Florida, U of Florida P 2008):
A plant that grows in unconsolidated sediments or on rocky subtrata that is impacted by sand scouring; these plants show specialized morphological and/or reproductive adaptations.
“Unconsolidated sediments” sounds to me like sand; not sure what else it could be (gravel or crushed shells, I suppose). And since psammo is Greek for sand, I’m going to say that it’s sand.
As far as seaweeds go, there are apparently all kinds of ways of classifying them. One is the various types of “attached macroalgae”: Psammophytic and lithophytic (lithos is rock) appear to be the binary categories here. The opposite of attached macroalgae would presumably be planktonic. As Dawes says, “most seaweeds are lithophytes that grow attached to hard substrata and form some of the most productive communities in the world” (17).
So what seaweeds are psammophytic? Well, to answer that question, I’d have to go back to the library, request an interlibrary loan, and reobtain my copy of Dawes and Mathieson. That sounds like a lot of work. What about a Google search?
Turns out that you don’t have to be a marine plant or algal growth to be a psammophyte. Any of those plants you see on sandy soil can be called psammophytic. So dune plants, like these lovely sea oats, would qualify:
Turns out it’s hard to see the sandy substrate in the shot above, so here’s a shot of a neighboring plant even closer to the water than that:
And, just in case you need some color with your sand-loving plants, here’s a beautiful, and endangered, psammophyte of south Florida: Beach Peanut (Okenia hypogaea)
I saw all three of these psammophytes on a field trip with the Florida Master Naturalist program back in 2008. But I hadn’t known the hard word that describes them all until I ran across it in research on the seaweeds of Florida. Now I have a fairly long agenda of photos to take when I get to the beach again…