Lichens (Cladina spp.) and (Cladonia spp.)
There are a half dozen species of ground lichens, or "reindeer moss" that sometimes carpet the sand in Florida scrubs. A lichen is not a single plant, but actually a combination of a fungus and an alga. Neither the fungus nor the alga can live alone, and the relationship is a type of symbiosis called obligate mutualism. Lichens are extremely slow-growing and very susceptible to air pollution. You won't find them in cities. Looking like puffy ground-clouds, top left, the gray lichens are Cladina evansii and the yellowish ones are C. subtenuis. Lichens have no roots, obtaining moisture instead from the evening air and the dew. They are brittle and crunchy underfoot when dry, but soft as cotton balls when moist. Ground lichens are killed by fire and slow to repopulate. The longer a scrub has been without fire, the larger and more numerous are the lichens.
These lichens, right, are Cladonia leporina, often called match-sticks or British soldiers. A similar species, not shown, is on the federal Endangered Species list.
The silvery lichens are silvery only when dry. As soon as Cladonia prostrata is wetted, the thalli (leaf-like structures) roll downward exposing a green surface, left. They do this in seconds, right before your eyes. Try it yourself.