Flavoparmelia caperata
Einar Tindal
Common Greenshield is one
of our most common lichens.
A lichen is special, because it is not one organism,
but two. A lichen is a complicated relationship between a
fungus
and an algae. A lichen is created when
the fungus and algae join together to form a new organism.
The lichen looks different than the way the fungus or algae
looks by itself. The lichen can also reproduce
itself and looks like a plant. The relationship between the
fungus and algae is not fully understood, but scientists are
studying to learn more. Ohio Division of
Forestry Copyright, Stephen /
Sylvia Sharnoff An interesting fact about
lichens is that the algae species in one lichen can usually
join with a different fungus and make another lichen. It
doesn't work the opposite way, however; a fungus is only
able to make a lichen with one type of algae. Although they look like
plants, lichens do not have roots,
stems, or leaves.
The lichen takes the form of the fungus, and the algae lives
inside. Since most algae are plants, they can make their own
food. The fungus part of a lichen gets its food from the
algae. Scientists cannot make up their minds if this
relationship is mutualism
or parasitism.
This may be a mutualistic relationship, since the fungus
gets food from the algae, and the algae gets a "house" from
the lichen. Or maybe the fungus is just a parasite, taking
food from the algae, when the algae could just as easily
live on its own or with another lichen. The fungus is able
to live on its own, but it doesn't do very well without the
algae.
Einar Tindal
A lichen species always
takes its name from the fungus part of the relationship. The
fungus in Common Greenshield is Flavoparmelia
caperata, so that is also the scientific name of the
lichen. Common Greenshield is
usually greenish-gray or yellowish-green. It is called a
"foliose" lichen because its body looks a lot like leaves.
The "leaves" are mostly round usually overlap. Sometimes
they are wrinkled, sometimes smooth. Common Greenshield grows
on tree trunks
or rocks. Some trees that often have greenshield on them are
maples and oaks. Lichens do not damage trees. Common
Greenshield grows well in shady, damp places, especially in
woods. Marie T. Trest, Wisconsin
State Herbarium
Einar Tindal