medulla in-between.
Lichen reproduction is a complicat-
ed affair involving the unique sexu-
al reproductive forms of the fungal
component as well as an asexual dis-
persal unit called a soredia, formed
of an algal cell entwined by fungal
hyphae.
Lichen species are typically named
after their fungal partner, but given
the complexities of their possible
relationships, naming and identifi-
cation can be difficult. In addition,
there are many different relation-
ships between fungi and algae that
do not result in what are considered
lichen. In an inverse scenario, there
are fungi that live within the tis-
sues of certain seaweeds. There are
also, in our weird world, green algae
that find a home on the surface of
mushrooms and fungi that parasitize
lichen.
Like many things in nature, lichen
are tougher than they look. They are
found in a variety of habitats all over
the globe, but they thrive in extreme
environments. Lichen play the long
game: go slow, stay small, and occupy
an unusual niche. They are most com-
mon where moisture is abundant, but
many lichen are highly adapted to
dry environments. They are the dom-
inant vegetation in the Arctic tundra
because they can survive in deep cold
and short day lengths as most tradi-
tional plants cannot.
Though lichen are often considered
to be pioneers of bare habitats, they
are not necessarily catalysts for suc-
cession in short timescales. Because
they tend to colonize spaces that
vascular plants cannot easily inhabit,
there are few plants that can replace
them. Their unique coalition of two
distinct organisms gives lichen a flexi-
bility of properties that most vascular
plants lack. Lichen cannot compete
with vascular plants on the plant's
favored turf, but they can live and
succeed in places where the plants
32
Trumpet lichen (Cladonia fimbriata) Photo by USFS
