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, far left, 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.
Plants of The Florida Scrub 
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, far left, 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. 
