Photographed in Rocky Point, Mexico. Any ideas about this plant? Thank you!
[Not really a precise answer (and I'm not a botanist after all).]
It's likely a lycopodiophyte. Looks like a Huperzia species, but it's impossible to tell exactly from the provided photo [if the species is not familiar, of course]. Of great help would be general appearance of the plant and form of sporangia.
You can try this key: Lycopodiaceae of North America.