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Posts Tagged ‘Green Shield Lichen’

This post was supposed to be part 2 of a lichen post I did back on November 29 but I’ve dilly dallied so long it would probably be hard for all of us to remember what was in that one, so I’ll just start anew. I do these lichen posts because people seem to be mystified by lichens and afraid they won’t be able to identify them. I’ll be the first to admit that identifying lichens isn’t easy, but I try to show lichens that are easier to identify than other species in the hope that you’ll give them a try. Often times when I go hunting lichens I start with a smooth barked tree like that in the above photo. As you can see it’s absolutely peppered with them and I can tell without even zooming in that there are at least 3 different lichens in that photo.

One of the lichens on that tree was this script lichen. Script lichens are easy to identify as such but breaking them down into species can be difficult. I think this one is the common script lichen (Graphis scripta.) Script lichens seem to be fussy about what kind of trees they grow on and the common script lichen prefers trees with smooth bark, like maple or beech.

The script lichen’s common name comes from its apothecia, which are its fruiting bodies where its spores are produced. They look like ancient runes that someone has scratched into the body of the lichen (Thallus.) Some appear as horizontal lines, some can be vertical or angular but most appear random like those in the photo. Some, like the asterisk lichen can be very beautiful but even though I’ve searched for an example for many years I’ve never seen one.

This script lichen had a very dark thallus and isn’t like any other that I’ve seen. I’m not sure what would make it so dark, but it might have been the cold. I’ve seen cold change the color of other lichens from gray to blue. From what I’ve seen of script lichens the body of the lichen is there year round, but only when it starts to get cold in the fall do the fruiting bodies appear. Many lichens choose to produce their spores in the winter and I’ve never been able to find out why.

One of the most common lichens seen on trees in this region is the common green shield lichen (Flavoparmelia caperata.)  They are large, leafy, round or oval lichens that are kind of a yellow green color, and colonies of them can cover nearly the entire trunk of a tree. They are usually very wrinkled and in fact the caperata part of the scientific name means wrinkled.

Seeing fruiting bodies (Apothecia) on green shield lichens is rare in my experience but they always seem to have abundant soredia, which are tiny, powdery vegetative reproductive bodies that can be carried off by the wind or rain to form new lichens. The soredia form on the body (Thallus) of the lichen in pustule like areas called soralia. They are very similar to other vegetative reproductive growths called isidia, which are stalked growths on the thallus. Some Native American tribes dried and crushed this lichen into a powder and used it to treat burns.

Bottlebrush shield lichen (Parmelia squarrosa) is very common but is also easily passed by because it often grows quite small and I find that its pale gray color blends well with the color of the bark of the trees that it grows on, like smooth barked maples. You can just see small shiny spherical dots on a few of its lobes in this photo. These are granular vegetative reproductive structures called isidia. When a squirrel runs up a tree and breaks these granular parts of it off, the broken parts will start new lichens. Lichens books say that fruiting bodies (Apothecia) are common on this lichen but I’ve never seen them.

The bottlebrush part of this lichen’s common name comes from its dense, dark mat of rhizines on its undersides. These rhizines can be thought of as tiny rootlets which help anchor the lichen to the bark of trees. When they are branched like a bottle brush they are said to be squarrose. This lichen will also grow on mossy rocks and likes shaded, humid places.

Yet another shield lichen usually found on trees is the hammered shield lichen (Parmelia sulcata.) Its common name comes from the way its network of sharp ridges and depressions makes it look like it has been hammered out of a sheet of steel. Fruiting bodies are said to be rare on this lichen, which explains why I’ve never seen them. Instead it relies on powdery, whitish soredia to reproduce. It also has rhizines like the bottlebrush shield, but they don’t seem as bushy and noticeable. Hammered shield lichens are relatively small and though the book Lichens of North America says they can even be weedy, I don’t see them very often.

It’s very common to be walking through the woods and find twigs and branches with large, leafy (Foliose) lichens like the one pictured growing on them. These lichens can be difficult to identify because they change color drastically when they dry out. Though this one appears on the gray side its normal color when wet would be a deep, olive brown. I think this one is in the Tuckermannopsis group, probably the fringed wrinkle lichen (Tuckermannopsis ciliaris.) Lichens in this group often have “wrinkled” in their common name because that’s the way they look. They’re very pretty and easy to see and I often find them on birch and white pine branches.

Fruiting bodies (Apothecia) are common on the fringed wrinkle lichen. They are also quite large and easily seen; shiny and brownish green. Tiny bead like structures called pycnidia line the margins of the apothecia. They are yet another type of vegetative reproductive structure that will form new lichens if they break off. This lichen or family of lichens is very common and I see them almost every time I go into the woods.

There are many beard lichens and many are abundant in this region, but one that I don’t see quite as often as others is the fishbone beard lichen (Usnea filipendula.) It grows high in the treetops and when I find it it’s almost always on a fallen branch, as this one was.

The fishbone beard lichen gets its common name not surprisingly, from its resemblance to the skeleton of a fish. Lichens in this genus contain usnic acid and have strong antiseptic and antibiotic properties. They’ve been used medicinally since ancient times throughout the world to stop bleeding and heal wounds, and also against lung and fungal infections. Native Americans moistened the lichens and used them as a poultice for boils and wounds.  Beard lichens are still used today in antiseptic skin creams, deodorants, and mouth washes. It is said that about 50% of lichen species have antibiotic properties and research to develop medicines from them is ongoing worldwide.

Man isn’t the only one who uses lichens. This bird’s nest had many beard lichens woven into it. One study that I read about said that 5 different species of lichen were found in just a tiny hummingbird’s nest.

Concentric boulder lichen (Porpidia crustulata) gets its name from the way its black apothecia grow in concentric (or nearly so) rings around their center. The gray body of the lichen forms a crust on stone and that makes it a crustose lichen. This lichen is relatively rare here and I only see them once in a blue moon. They grow in sun or shade and don’t ever seem to change color.

Another shield lichen that’s very common in this area is the peppered rock shield (Xanthoparmelia conspersa.) It grows on stone in full sun and I usually find it on old stone walls. It’s a big lichen, often 10 inches or more across, that seems to be almost always fruiting, with crinkly brown fruiting bodies (Apothecia.) Though it must produce an abundance of spores this lichen also reproduces vegetatively, again by the granular vegetative reproductive structures called isidia, like the bottlebrush shield lichen we saw earlier. When bits of the lichen are broken off the isidia increase its chances of starting a new colony. Isidia also increase photosynthetic efficiency.

Here is a closer look at the peppered rock shield’s apothecia. They are big enough to see without any magnification and are an orangey brown color.  You can also see bits of the insidia. It’s clear that this lichen is all about continuation of the species and it does well at it. One stone wall I know of has them on almost every stone in the wall.

The golden moonglow lichens (Dimelaena oreina) that I see are usually about an inch across but they can get much bigger. They grow in full sun on granite and don’t seem to change color when they dry out like many other lichens do. The one in the photo was producing spores and that’s something I don’t see this lichen do very often. If you spend much time in cemeteries you have probably seen this pretty lichen, because it seems to like growing on smooth, polished stone. It is a crustose lichen, so removing it from any kind of stone would be a challenge. When lichens grow on glass the acids in them can actually etch the glass and this is a problem in the big European cathedrals, especially.

Rock foam lichens (Stereocaulon saxatile) grow directly on stone in full sun. When dry this lichen is very stiff and brushy and almost seems as if it would cut you but caribou will eat it when they can’t find reindeer lichens. This lichen is often used by prospectors because a simple lab test on it will show what type of stone it was growing on and what minerals, like copper for instance, are in the stone.

Lichens, as I hope these lichen posts have shown, can be very beautiful, and one of the prettiest I’ve seen lately is the frosted comma lichen (Arthonia caesia.) Its blue gray apothecia against a yellowish gray body make it easy to identify but you have to look closely to see these features. This one was no more than a half inch across and the blue apothecia were about the size of a period made by a pencil on paper.  I hope you’ll take the time to look for it and other lichens on your next nature walk. They can be found virtually anywhere at any season, and are always interesting and often beautiful.

We keep seeing things all our life, yet seldom do we notice them. ~Avijeet Das

Thanks for stopping in.

 

 

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