Lichens

Some people think that once the leaves have fallen there is nothing left to see outside until spring, but they couldn’t be more wrong. Lichens for instance, are there year round and unless you live in a place with poor air quality they are everywhere; on trees, on stones, on the ground, and even on buildings, roofs, windows, and sidewalks. They are like small jewels that have been sprinkled throughout nature. Common goldspeck lichens (Candelariella vitellina) for instance, are uncommonly beautiful. Look for this bright yellow crustose lichen on stone. It’s a very artistic lichen and I like the patterns that it makes. I see it on gravestones quite often.

It shouldn’t come as a great surprise that, at high magnification, the body of the common goldspeck lichen looks like it’s made up of tiny golden specks. The book Lichens of North America describe the body of this lichen as “little cushions of flattened granules.” This lichen is sometimes sterile, with no fruiting bodies present, but this one appeared to have a few. The bluish color in the background is the slate that it grows on.

This is an odd lichen with large white fruiting bodies (apothecia) that look like they just erupt anywhere on the body (thallus) but also look like they are stalked, depending how you look at them. Some are convex and some concave and some have rims and some don’t. The white apothecia and green body with flattened strap like branches tell me that it’s probably the tufted ramalina lichen (Ramalina fastigiata.) A lichen guide from 1902 says this lichen is “very common in New England” but I know of only one place it grows. It is apparently very sensitive to air pollution as many lichens are. If you live in a place with a lot of lichens, breathe happily.

Bright yellow fringed candle flame lichens (Candelaria fibrosa) will often cover entire tree trunks. It must like a lot of water because I see it a lot on the lower parts of trees that grow near irrigation systems, with trunks that are almost always wet in warmer months. Seen up close this lichen always reminds me of scrambled eggs. I call this the “downtown” lichen because I see it a lot there.

It’s interesting how nature seems to use the same shapes over and over again in different ways. The round fruiting cups, called apothecia, of the Poplar Sunburst Lichen (Xanthoria hasseana) remind me of the suckers on an octopus or squid. Instead of latching onto things however, this lichen uses its cups for spore production. To give you a sense of scale-the largest of those in the photo is about an eighth of an inch across. The entire lichen might have been an inch long.

This example was even smaller at about the size of a penny (.75”) and was more apothecia than thallus. Spore production is what it’s all about because that’s what ensures continuation of the species.

The apothecia on this star rosette lichen (Physcia stellaris) are a good example of how colors can change, even on the same lichen. This lichen has dark brown apothecia that are often pruinose. Pruinose refers to the white, waxy, powdery coating. You’ve no doubt seen examples of this waxy “bloom” on blueberries and plums. I’ve noticed by watching lichens that have pruinose apothecia that the coating can reflect light in different ways, sometimes appearing gray and at other times more blue, and sometimes even black. The apothecia on this lichen often show a range of colors, from brown to light blue. The way the sunlight strikes it has a lot to do with its colors.

I think this is the smallest example of a Cumberland rock shield lichen (Xanthoparmelia cumberlandia) that I’ve ever seen, but even at its tiny 1/2 inch size it was beginning to produce spores in its brown apothecia. This lichen likes to grow on boulders or other stone. The body (Thallus) is described as being “yellow-green to sometimes bluish green” and the fruiting discs (Apothecia) are “cinnamon to dark brown.” The body of this lichen always looks like someone dripped candle wax on the stone to me. This one was very symmetrical but they are usually asymmetrical.

Smokey eye boulder lichen apothecia (Porpidia albocaerulescens) are usually a smoky gray color, which is where their common name comes from, but they can also have a bluish tint because of the way their waxy (pruinose) coating reflects sunlight. In this case the body of the lichen is a grayish color but it can also be a brownish gold color. One of the things that can make lichen identification difficult is the ability of some lichens to change color in different light, and this is one that does that. It can look very different from just a few feet away. This is a crustose lichens and it forms a kind of crust on the substrate that it grows on. The bond between a crustose lichen and its substrate is so strong that it can’t be removed without damaging the substrate.  

British soldier lichens (Cladonia cristatella) like to grow on damp wood like rotted stumps and logs, but I’ve found them on buildings, fence posts, and built up forest litter on boulders. At this time of year I don’t pass too many mossy old tree stumps without having a glance for British soldiers. Their bright red apothecia make them easy to see, even if you’re colorblind.

Shrubby little beard lichens are fruticose lichens, and fruticose lichens have upright or pendulous branches. I think this one is a bristly beard (Usnea hirta) but it might also be a young fishbone beard lichen. Though it grew on the shadier side of a tree it was caught in bright sunlight, and I’d guess that it must get an hour of sunlight a day. One way beard lichens reproduce is by fragmentation. Pieces break off and are carried by the wind or maybe animal fur to another spot to colonize. There are many of these high up in the trees and they come down, often still attached to the branch they grew on, during a good wind. I’ve found as many on the ground as I have on trees.

I’ve been trying to identify this beard lichen for years with no luck. Maybe it’s just a different colored example of the bristly beard seen previously?

Common greenshield lichen (Flavoparmelia caperata) is indeed very common. It’s a large lichen and colonies of them often grow big enough to cover entire trees. They often wrinkle like the example seen here. Like many lichens they change color, and go from grayish when dry to yellow green when wet. This example was dry. This lichen also taught me that many lichens prefer growing on the shady side of trees, presumably so the sun doesn’t dry them out quite so fast.

Hammered shield lichens (Parmelia sulcata) are on the rare side here but I see them occasionally, always on trees. There didn’t seem to be anything special about the deciduous tree they were on, this time but it was in a sheltered spot like the last tree I found them on. Hammered shield lichen is said to have a large variety of named varieties and forms, so it can be tough to pin down.

Hammered shield lichens are silvery gray and their many sharp ridges and depressions makes them look like they’ve been hammered out of a piece of steel. Fruiting bodies are said to be rare and I’ve never seen them. It is said to have powdery, whitish soredia but I’ve never seen them either. Soredia are tiny packages of both fungus and alga that break off the lichen. They are simply another means of reproduction.

I find pebbled pixie cup lichens (Cladonia pyxidata) growing on soil or rotting stumps and logs, and occasionally on stone. Pixie cups look like tiny golf tees or trumpets. They are squamulose lichens, and the golf tee shapes arise from leafy growths called squamules. A squamule is a lobe of the body of the lichen (thallus,) and  squamulose lichens have small, leafy lobes like those at the base of this example. The cup is so small even a pea would seem huge in comparison.

Though pixie cup lichens are squamulose they have fruticose fruiting structures called podetia. The parts that look like tiny golf tees are its podetia. “Podetia” describes a stalk like growth which bears the apothecia, or fruiting bodies. This example has some almost microscopic dots around the rim, which are its apothecia. Finally, frucitose means a lichen has a bushy, vertical growth. Since this example has squamules even growing inside the tiny cups it must be a pebbled pixie cup lichen.

If you spend time walking along old stone walls eventually you’ll see a stone with a splash of bright orange on it and it will probably be the sidewalk firedot lichen (Caloplaca feracissima,) so called because it is a lime lover and grows on concrete sidewalks, which have lime in them. When you see it in a stone wall it’s a fair bet that the stone it grows on has limestone in it too. This stone is almost completely covered by it.

A closer look at this example of the sidewalk firedot lichen showed it was very dry. Lichens are at their best when they are wet because that’s when they’ll show their true colors and size, so that’s when serious lichen hunters look for them. A misty or drizzly day is perfect but we haven’t had one in a while.

Some lichens might look like they have little spiders on them, or maybe as if they had been carved with a pocket knife but no, the squiggly lines are the apothecia of the script lichen (Graphis scripta.) This lichen usually prefers trees with smooth bark so I was surprised to see it on this rough barked tree. From what I’ve seen they only produce spores in winter. You can walk right by a tree full of script lichens in summer and see only grayish spots with no apothecia at all. In fact many lichens seem to prefer winter for spore production and I’ve never been able to find out why.

Next time you find yourself walking outside after a rain I hope you’ll take the time to look a little closer at all those colored spots you’ll see on the trees, stones, soil, and even sidewalks. If you do a whole new world of nature study will open for you.

There is a low mist in the woods. It is a good day to study lichens. ~Henry David Thoreau

Thanks for stopping in.