Hello friends! Good afternoon and welcome
to Florida Supernature!
Today's presentation on the Life of
Lichen. I'm James Stevenson, I am with the
University of Florida Institute of Food
and Agricultural Sciences, Pinellas
County Extension. We're a partnership
with our local government, providing our
citizen's some research-based
information on how to be good stewards
of the bit of the environment that we
have purview over. Today we'll be
discussing this incredible creature,
organism, called lichen; and you've
probably seen, you might even have heard
of lichen, but we're gonna dive into just
exactly what is it and how does it work. Now, most people, if they are slightly
aware of lichen, would be able to say
that yes it's a combination of two
different organisms: of fungus and an
algae, and to an extent that is exactly
right. A lichen can consist of a fungus,
and we're all familiar with toadstools. We know what fungus is, and algae an
aquatic plant, an aquatic photosynthetic
plant.So: fungus and an algae.
The algae provides sugar alcohols, sugar,
glucose, that plants have the magic
ability of being able to create from
sunlight and carbon dioxide.
The fungus provides support; a place for
that algae to live. That's how those two
things come together to form a lichen
organism. But there are some lichen that
are combinations of fungus, like we have
our representative fungus here, our
toadstool, and bacteria. There are
bacteria which belong to a completely
different kingdom of life; they're not
plants, they're not animals, they're not
fungus, they're bacteria that can
photosynthesize.
So there are photosynthetic bacteria
that can be involved in a lichen
relationship. So again, the bacteria is
photosynthetic, it can produce the sugar,
glucose, that the fungus can feed off of,
and it can also produce nitrogen another
important nutrient for many living
things. Getting a little bit more
complicated, a lichen can consist of all
three organisms: a fungus, an algae, and a
bacteria. So that shows you how diverse
this group can be. Just, you know,
exponentially more diverse depending on
the combination of different fungal
species different algae species and
different bacterial species. So let's
look at the fungus first. The fungus in
a lichen is referred to as the mycobiont
that means the the fungal part of
this living organism. The mycobiont, now
here I want to pause and just remind you
of some you know eighth or ninth grade
biology: living organisms are separated
into very different kingdoms, and at the
very, very, very basic level, they can be
broken down into these five basic
kingdoms. The bacteria as a very diverse
kingdom and we all know that certain
bacteria can cause disease but they're
also very important
decomposers. We have the protists, perhaps
you remember the Paramecium from school
(maybe not, anyway) these are single-celled
organisms that don't, that are more
complex than bacteria, reproduce
themselves usually by budding off. The
fungus is a separate kingdom. The plants
is a separate kingdom, and the animals.
And if you think about the diversity of
animals, everything from, say, a flea on
your cat to a great blue whale, a little
bit of diversity in there yeah? So all
these kingdoms have just about the same
amount of diversity amongst the
different members of those kingdoms. So
just bear that in mind because what
we're talking about today are bacteria
in one kingdom,
fungus in another Kingdom, and plants in
another Kingdom, all coming together to
form these complex organisms known as
lichen. Back to the subject of fungus
fungus or fungi are composed of hollow
tubes called hyphae. And most fungus that are
composed of this hyphae spend the
majority of their lifecycle out of sight
as these closed hollow tubes called hyphae. You might have heard that fungus
reproduces by spores, and when a spore
germinates it becomes a little germling,
(that a cute little word germling) and
then it begins to grow and grow and as
it gets bigger creates these partitions
called septa, and that forms the hyphae.
The apical cell here continues to grow
in a particular direction these hyphae branch
and form vast, vast networks of hyphal
fibers, hyphae fibers. The way that fungus
works is that they digest their
environment; they do not ingest their
environment the way that we do when we
eat our sandwich or salad we're
ingesting the environment. The way that
fungus works is as the hyphae grows, they
secrete digestive enzymes into their
environment, degrade that substrate, that
environment, and then reabsorb. So they
don't physically eat they just kind of
reabsorb their nutrients that way, and
that is how the fungus makes its living!
by usually inhabiting whatever it is
that it is going to be breaking down and
ingesting, and you want to get a little
bit gross you can imagine if a fungus
were to be a an animal pathogen that
thing that they live inside and digest
and reabsorb would be a living creature!
And of course there are some we know;
some fungal diseases, and that's what's
happening, we're being invaded by these
mycelia, these groups of hyphae together
are referred to as mycelium or as plural
mycelia. Those fungal species, and many
are decomposers of wood, if you find a
rotten log you can often break it apart
and find masses of hyphae, this
network, this vast network of those
hollow tubes decomposing that wood,
rotting that wood down and reabsorbing
all the nutrients that that tree spent a
lifetime locking up into its structure. So that's how the fungus works overall,
but I did mention that fungus is a
kingdom and so there are very many
different, remember the flea and the
great blue whale analogy? there's lots
and lots of variation within the fungal
Kingdom. And we're probably familiar with
the toadstool. If you were to, you know, if
somebody were to ask you to draw a
fungus you might draw a toadstool
because that's kind of everyone's go-to, as it were,  but there's a lot of
diversity as I mentioned in the fungus.
You might also be familiar with the
bracket fungus that you might see
growing out of a tree especially a dead
tree. Bread mold is a fungus that many of
us may or may not be familiar with. There's a group called yeast maybe
you've heard of yeast? yeast is an
incredibly specialized single-celled
fungus, these are very highly evolved, if
you wil,l they evolved from much more
complicated like the toadstools and the
brackets but they've forgone this rather
garish lifestyle and they're just the
single cell and they bud and they
reproduce and they absorb sugars they
feed on sugars in their environment and
of course they release carbon dioxide
and that is why the yeast is so
important in bread making it's what
makes the bread rise by its reproduction
and respiration. But there's
another group of fungus that create
these little cup structures, and this is
a group that are very often lichenized.
These cup fungus are very often
associated, not always but often,
associated in lichen organisms. They're
referred to as the ascomycetes.
As you might remember from, before the
mycobiont, myco means fungus the asco-
refers to this cup shaped structure and
so here is an ascomycetet fungus
producing these cup shaped structures
for reproduction only. I do want to
mention that the the part of the fungus
that we can actually see, these in the
case of these these above-ground or
sticking out of the side of a tree, this
is what happens when the fungus is ready
to reproduce. All those hyphae, all that
mycelium, all those fibers, they begin to
knit together into this very solid
structure and diversify into the various
parts including the structures that are
going to produce the spores to reproduce
the species. So a fungus can live
actually for years as mycelium
underground or in a in the bark of a
tree or whatever environment it is
digesting, and then only occasionally
will those hyphae, that mycelium will
 knit together to form this
reproductive structure. So what you see
above ground is only the tip of the
iceberg. Most of the fungus is hidden
within whatever environment it lives in.
So this group the ascomycete is often in
lichen relationships. Is that okay? can
we move on to the algae? I hope
everybody's doing well today...The algae,
of course, a type of plant, usually
aquatic plants. In a lichen organism
they're referred to as the photobiont:
"photo" for light "biont" again for
life form.
Because, of course, the the photobiont
is the one that is going to be turning
the sunlight, the photons, into sugar
through the magic of plants. One genus
of algae that is often lichenized is
one called Trebouxia, and that's a green
algae, you can see the little
photosynthetic cells here, and these
other structures that it kind of forms
these colonies. The Trebouxia algae.
Another is Trentepohlia. Now, it's not
important to remember these genera, but
it's just something that there's only a
handful of algae that have found
themselves kind of, kind o,f *abducted* as
it were, into lichenized structures. Both
of these genera: Trebouxia and Trentepohlia, are quite able to live on their
own; they are evolved genera with its
evolved species that have their own life
cycles and habitats and way of living. They do not need to be lichenized in
order to survive. The fungal component of
lichen however, is unable to survive even
in a laboratory without its photobiont, so
it's kind of like the
fungus holds the algae hostage, right?
Another photobiont the cyanobacteria
which we used to call the blue-green
algae. This is, again, remember that
kingdom bacteria that is different from
plants, it's different from fungus, it's
its own thing, but this is another group
that has developed the ability to
photosynthesize, a bacteria a
photosynthetic bacteria that is also
often lichenized, is Nostoc. And Nostoc
is also perfectly capable of
living life on its own outside of a
lichenized relationship. It's not
symbiosis (the word just came to me) it's
more of a prison situation, where the
lichen organism consists of these fungal
hyphae (remember those hollow tubes?) this
represents those hollow tubes of fungus.
They form a nice body layer that can
adhere to whatever surface this lichen
is going to be growing on. They produce a
skin on the surface to prevent drying
out and somewhere in the middle it keeps
its (it kind of imprisons, as it were) it's
photobionts,
either the algae or the bacteria or both.
So we have this layer of the photobionts suspended in all that hyphae; thinner
on the top to allow for gaseous
exchange, to allow
for sunlight to penetrate, to activate
the the chloroplasts and get that sugar
factory going, and thick enough on the
bottom to support the whole structure,
the whole organism, and adhere it to
whatever surface it's growing on. And I
like to kind of compare this setup
to the setup of Recee's cup, and if we were
face-to-face this afternoon I would, at
this point, hand you a little Reecee's cup
because it's kind of mean to show you a
Reecee's cup and not give you one, so
forgive me for that, take a raincheck,
come and see us when all this mess is
over and I'll certainly hook you up with
a Reecee's cup. But again, so we have the the
fungal structure supporting that
precious layer inside of what, in the
case of a lichen, would be the photobiont,
or the photosynthetic organisms. Now, that's the basic, basic of lichen and
scientists have been able to pull apart
lichen, identify the fungal component
give it a name, identify whatever the
photobiont is by growing them separately,
as long as they can keep the fungus
alive,
figuring out what kind of fungus it
would be if it could live on its
own, but there were some mysteries there. Oftentimes the same species of fungus
and algae and bacteria would appear in
lichen that are very different from each
other. So look, we've got the same
organisms but when they combine
naturally they become these very, very
different things, and it turns out, and
it's only been in the past five or ten
years or so, that a fourth member, a
fourth component to a lichenized
situation has been identified, and it
would be a yeast. And this is a picture
of those (if you remember a yeast is
another kind of fungus, a very
specialized kind of fungus, single
cellular that reproduces by budding) and
that the presence or absence of that
yeast, whatever genus of yeast
(there are yeasts that  are
cup fungus that have formed yeast types
there are those toadstool types that
have formed yeast general as wel)l so
yeast across the board can be very very
variable as well, as simple as they are
and as specialized as they are, they can
exist with very different genetics, and
it's the genetics of the yeast that can
allow the expression of different
species of lichen that previously were
thought to consist of just two or maybe
three different organisms living
together. This solved that mystery and
why we can have such diversity in lichen.
So you've got all this mess going on,
you've got fungus, you've got bacteria,
you've got yeast, you've got fungus, how
on earth would you reproduce that? Well,
the easiest part would be to break
into little bits. If you've ever taken a
cutting you know you can grow a whole
new plant from just one little piece.
It's the same kind of idea with certain
lichen reproduction. Here we have that
Reecee's cup kind of split open on the
surface, and we've got a little bit of
the peanut butter layer and a little bit
of the chocolate layer
kind of escaping into the environment to
establish. The fungus would then begin to
grow into this thallus which
refers to the body of lichen, and the
little captive photobiont orbionts
would then again go through their
reproductive phase as well just
splitting into every couple days, or in
some cases a couple hours, to reproduce
this species. It's
cloning itself basically into these
little bundles of everything that that
parent lichen is composed of. Here's a
scanning electron picture of one of
those soredia, those little packages of
everything you need to start a new lichen
species. Now, the diospores, the little
bundles, they can come from within, in the
case of a lichen forming a structure
called a soredium, it's a little
nursery area where they can assemble all
these pieces and send them out into the
atmosphere, or they can exist in these
kind of baton shaped structures that
stick up over the surface of the lichen
and they can be brushed off or blown off.
And these diospores, these little
bundles can be released into the
environment that way. Here's a picture
that we took here at Brooker of a tree
trunk that had some of those isidia,
you can, I hope you can, notice that these
little structures are kind of warty?
they're kind of like, they kind of stick
up you can see they're even kind of
granular because they've got everything
they need to reproduce whatever species
of of lichen that would be. Pausing
here to say lichen, of course, can also
form by chance and they must have formed
by chance there's no other way that
lichen could have come into existence. So
let's say that the this particular
species of fungus within this lichenized
organism was able to produce a
fungal spore (and it can) and release that
spore into the atmosphere which it can do, 
if that spore were to, by chance,
encounter exactly the right species of
bacteria, yeast, and algae, a lichen
could could form from that chance
encounter. And it has done, and it can do
again. So as the odds seem so insanely high
that that could actually happen, but
obviously that's how lichen originally
came into existence. So let's look at
some lichen biodiversity, some of the
different ways that lichen grow, and
express themselves. And although there's
thousands of species of lichen, there's
three basic growth forms. And if that's
all you learned about lichen today, and
if that's all you can take away from
today's presentation, that'd be great. You
can, you can do a lot of showing off on
your next hike if you know these three
things! And I hope they're easy enough to
remember. Three growth habits: crustose,
foliose, and fruticose. And these actually
have little clues in a couple of their
names. Crustose, you've probably heard
the word "crust" before; it it's the same. Foliose,  have you heard of foliage? foliar?
having to do with being LEAF-like
exactly! And fruticose, I'll give you
this one because it's not very obvious for free, because in botany it means "growing
like a shrub." So we've got crusty lichen
leafy lichen and shrubby lichen; those
are three different growth forms that
exist throughout the entire diversity of
lichenized organisms. Here's an example
of a crustose lichen so, this is the
trunk of a tree and the lichen looks
more or less like it's been painted on.
This orange represents the body or the
thallus of the lichen, these raised parts
are the reproductive structures
of a particular type of crustose lichen, and
so even within those three growth habits
there are different types. This type of
crustose lichen is a script lichen. "Script" because it appeared to someone
that these little reproductive
structures look like they might be, you
know writing, something trying to
communicate,  maybe it is!
doubtful but... So we have this scribbling,
so these are referred to as the script
lichen. They're quite fun to find. We've
also got another here at Brooker Creek
Preserve, we have a popular pink lichen. It catches a lot of people's attention
because "what's that pink paint doing all
the way up in the top of the tree up
there?" it is a crustose type lichen,
and it looks as though it, as I said, has
been painted on. This is the Christmas
lichen, some people refer to it as Baton
Rouge which means "red branch" because the
presence of this lichen and they can
form very large areas of growth makes
the branch appear to be red or pink.
So Christmas lichen, Baton Rouge, take your
pick. No matter what, the scientists refer
to it as Cryptothecia which means
"hidden body," rubrcincta which means
"painted red." So there's the Christmas
lichen. It is often cited as sensitive
to pollution, and lichen has actually
been used to do air quality studies. The
presence or absence of certain lichen in
certain areas
along with other data can assess the air
quality of a particular area. Where
you see Cryptothecia rubrocincta, or
whatever else you want to call it, pretty
well pretty well assured that there's
clean air around, so breathe deep every
time you see the pink lichen on the
branches. Of course it has another name
Herpothallium... don't worry about that. Let's let's let's move on...
Another script lichen which is another
crustose, or crust-like, or painted on,
(you get the idea) 
these are very closely associated with
whatever substrate they are growing on. Another point to mention if you see lichen
growing on your patio, or if you see
lichen growing on your house, you can
attest to the fact that lichen does not
derive any nutrient from whatever it's
growing on. It's not a parasite. The
lichen that grows on the branches of
trees is not deriving any nutrient from
that tree; it's not causing any damage to
that tree whatsoever. It's simply trying
to get a place in the Sun. The second
growth habit and there are many
different types of foliose, remember, the
leaf like lichens? This one is one of the
ruffle lichens or Parmotrema, and if
you see, you can get your fingernail in
there and flick it up like a leaf. Parmotrema
very, common up here at Brooker
Creek, very common in Pinellas County,
this one certain species within this
genus can tolerate quite a lot of
pollution, so you can find these in town. These are much more likely to be found
in town, and they're kind of a bluish
gray color, oftentimes with these strange
outgrowths on the edges like eyelashes
(we call them) but look if you look really
closely can you see these little cups? Those are the expression, that that's the
fungus expressing itself and trying to
reproduce itself as a fungus only.
Remember the cup shaped fungus in the
very beginning? Obviously there is one of
those types of fungus associated in this
lichen, and it's produced that same
little cup, and it's going to produce
just fungal spores in the off chance
that that spore is going to find
whatever else it needs
to go into this lichenized genus, Parmpotrema.  Another one
of the shield lichens, again its leafy,
you can see how you can just lift this
up on the edge (I hope you can anyway). I
found this one here at Brooker and I was
hoping that it would be a type of foliose
lichen called lungwort because the
name is so disgusting, and I wanted to
say that I'd found a lungwort. Could be,
if you look you might be able to see the
veination within the thallus of this
lichen? is kind of like a network like,
apparently like lungs are inside, so that
could be a foliose type lichen called
lungwort. The third group are the fruticose
remember that what that means?
fruticose? i gave it to you? did you
write it down? it doesn't matter...fruticose means it grows like a shrub. So
this is a terrestrial lichen, it's
growing like a shrub on the ground. This
one is called deer moss but it's not
moss it's a... what what are we talking
about here today? lichen! it's a lichen,
it's a 3-dimensional shrub like deer
moss and, I thought that the deer would
use this only as famine food. Further
north this genus, Cladonia, is called
reindeer moss, but of course it would be
silly to call this reindeer moss in
Florida. And reindeer have been seen, have
been known to dig through the snow find
Cladonia, find some of this reindeer moss
in their case, and eat it in the middle
of winter when there's nothing else. And
I made the assumption that our native
deer here in Florida would use this
organism in the same way: as famine food,
when there's
nothing, well there's hardly ever nothing
to eat year-round in peninsular Florida
is there? but sure enough one day we were
taking a walk and we came around the
corner and there was a young deer and he
had his head down behind a saw palmetto,
and he came up and it was just deer
moss all, just all, he was lovin' it! So
apparently it's not famine food for our
native deer. British soldiers. It's, I
think that's the same slide that I have
in my background right now, this is a
fruticose type lichen, so you can see
the little stalks, so it's growing on a
stalk and on the top, the reproductive
structures, the isidia, they're bright
red. So they're 
little British soldiers with their
little red caps. Sometimes it's called a
match stick lichen because these little
stalks that stand up above whatever it's
growing on like a matchstick. Cladonia
cristatella, across Europe, Asia and North America,
it's everywhere. Same species. The beard
lichen is Usnea, and Usnea actually
means "beard." And look! a cup! these little
cups the fungus is trying to express
itself, trying to create reproductive
spores to allow the the fungus to
reproduce itself and in the off chance
again, that it's going to encounter
whatever components it needs to re-lichenize and form that organism anew. So
that's a brief life history of these
interesting organisms.
I hope it's inspired you to go out and
look for some of these things, explain to
your friend how they're growing, and pass
this knowledge along, especially the part
about they're not parasites, and they're
not doing any damage. If there's a tree
that's in decline for whatever reason
small tree or a large tree that is just
getting old, (and things
wear-out) the lichen could certainly
continue growing because there, they've
got everything they need. But as the tree
declines it might appear that the lichen
is taking over but again it's not
deriving any nutrient from whatever it's
growing on and: think about it: if the
tree were to fall to the ground and die
that's the end of all the lichen as well.
So lichen: not a parasite, not a pathogen,
just a hanger-on trying to go through a
life cycle and make a living. I hope you
enjoyed today's presentation, I'm James
Stevenson with the University of IFAS
Pinellas County Extension if you have
any questions or comments or complaints
or ways that we could make our
presentations better please don't
hesitate to contact me either at the
email address right underneath my face
or this one here my pinellascounty.org
address. Next week
Florida Supernature will bring you
Botanical Science for Beginners, that's
quite fun. We used to call it Botany
101, but I think the word botany scares
people, so we added the word "beginners." I
promise not to scare you off with
botanical science for beginners. The
following week we'll be doing Kitchen
Botany here, same place, same time,
exploring what you already know about
botany through your experiences with
salads and cooking and so on. To sign up
for the series of or each class at a
time you probably managed to navigate
your way to bit.ly/FL
super nature. You can keep up with all of
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following us at our Brooker Creek
Environmental Education Center Facebook
page. Again thank you for joining us
today I hope to hear from some of you
and I hope to see you back here soon
thanks and have a great afternoon.
 
