Lichens are harder to identify with certainty than flowering plants, trees and ferns. The following are my best-guesses using Lichens of North America by Irwin M. Brodo, Sylvia Duran Sharnoff, and Stephen Sharnoff as my main guide. However, I may well have misidentified many and corrections are welcome.
Translation of the Latin and Greek names is tentative - from my own investigation.
The thallus is just a vague stain or nil. The yellow dots are apothecia. Under the magnifying glass, little yellow blobs, singles or a few together. Seen on the bridge railing in a few places. Very small patches that have to be looked for. In Lichens of the Ottawa Region, "very common".
My notes: There are more of these on the railings than meets the eye. The apothecia can be brownish in colour. Like little blobs or helmets.
calo = beautiful ; placa = place or patch (Greek) holo = whole; carpa = carpel, the stigma+style+ovary of a flowering plant
Firedot lichen
Cladonia chlorophaea Mealy pixie-cup
Habitat: wood, bark, rock or soil Where found: boulder by parking area
I thought it was C pyxidata but EB thought not My notes: "Trumpets" are gray with green flakes (thallus squamules?) dotting the inside and some on the outside. Sometimes these are so abundant that the trumpet itself looks green. Some of the flakes are larger than the rest which are very small. On rocks with moss.
clados = sprout or branch (Greek)
Pebbled pixie-cup
Conotrema urceolatum Can-of-worms lichen
Very small black dots on white patches on trees, usually sugar maple. The dots can only be seen up close. Otherwise it looks like the bark has been painted white.
Can-of-worms lichen
Flavoparmelia caperata Common greenshield lichen
Useful features for identification are its yellow-green colour (EB) and wrinkling of the upper surface. Lower surface black with brown edge. Black rhizines.
My notes: Quite common on the bridge, often large patches in the company of rough speckled lichen and hammered shield lichen. Much greener than the others. Some of the upper surfaces are not wrinkled.
Common greenshield lichen
Graphis scripta Common script lichen
This looks like circles and ovals of white paint on tree trunks in shady areas. A closer look shows small black squiggles laid upon the white patches. These are called lirellae and contain the sacs that hold the spores.Very common.
My notes: The white patches often have a tint of green/gray which distinguishes them Conotrema urceolatum from a distance. On the same trees are often seen patches or bands of whiter colour which show no lirellae and look like paint. I don't know what these are.
Common script lichen
Lepraria lobificans Fluffy dust lichen
Commonly seen on trees especially at bases as a mint green amorphous powder easily rubbed away,
Parmelia sulcata Hammered shield lichen
Or possibly, P. squarrosa but likely not since latter has rhizines extending to edge of lobes and not stated to commonly grow on wood. The immediate useful identifying feature seen well with a magnifying glass is the cracked-looking surface as if hit with a hammer. Underside is black with rhizines.
My notes: Some of the upper surfaces don't look as "hammered". The surfaces are shinier than other lichen. There are not many blemishes. Yet a named feature is many isida. Re EB, young specimens may be fairly unblemished. The lobes are fairly squared off. Often in company of rough speckled shield lichen which has bigger, rounder lobes, profuse white isidia, black dots too and has a tan undersurface without the thick black rhizines of Parmelia sulcata. The edges can sometimes be brownish but less so than rough speckled shield lichen.
Hammered shield lichen
Peltigera canina Dog pelt lichen
This lichen grows on soil and I think is quite well camouflaged especially after rain. The underside has white "veins". Peltigera rufescens has brownish veins. I seemed to see both in the same patch and so am not entirely sure if this is canina or rufescens. Re EB, more likely P rufescens. I will look at it again,
Location: a tree along the bridge Positively identified: Very small lobes (1 mm), occasional orange medulla seen; black rhizines with white tips under microscope.
Physcia adscendens Hooded rosette lichen (The gray lichen at the bottom of the picture)
A profuse lichen. Some lobes form raised hoods. With a good magnifying glass and especially under the microscope, remarkable gelatinous-looking cilia stick out from the edges of lobes, like catfish whiskers. The yellow lichen, I believe, is Xanthoria polycarpa (see below).
Hooded rosette lichen (gray one)
Porpidia crustulata Concentric boulder lichen
Habitat: siliceous rocks, especially pebbles and small boulders Where found: boulder beside parking area
Or, possibly: Porpidia albocaerulescens (Smoky-eye boulder lichen) or P. macrocarpa, all three being common in our area. (Check if pruinose.)
Concentric boulder lichen
Punctelia rudecta Rough speckled shield lichen
Blue-gray foliose, lobular lichen covered with white dots (isidia). Round mitten-like lobes many with shallow indentations. Underside is tan with short pale rhizines seen well under the microscope. On the bridge railing, many examples. Small groups. Seen also on rock.
There are four species of Xanthoparmelia in our region (LOR p 115). Three are common, one infrequent. Two have rare apothecia and so are ruled out. X somloensis has narrow strap-like lobes, squared off. This one has more rounded, somewhat broader lobes and a black margin under the microscope. Apothecia have rolled in margins. It forms a very large patch. Therefore I identify it as X cumberlandia.
Cumberland rock-shield lichen
Cumberland rock-shield lichen
Xanthoria polycarpa Pincushion sunburst lichen (The yellow lichen pictured, not the gray)
Rather featureless upper surface. Lower surface is white with no rhizines that I see. Lobes are very small, under 1 mm and overlap. Many apothecia - spore-containing structure. These are round with a thick border that is the same colour as the full lichen (thallus) but with a central disc that is darker yellow.
LICHENS IDENTIFIED
Description: a yellow lichen which looks mostly like Candelaria fibrosa but it is considered rare. Other possibilities are Candelaria concolor which is common on ash but apothecia are uncommon and there are many here. It could be Xanthoria hasseana which is most common on polar and said to have dark orange apothecia whereas these look more yellow. My location: On a branch of the poor-shape ash at our parking turning place
Cladonia fimbriata (Trumpet lichen) Description: Under the microscope fine granular podetia My location: near Donald's boat
Cladonia pyxidata (Pebbled pixie-cup) Description: Under the microscope green squamules attached to the inside and outside of the cup. Brown apothecia at the rim. My location: near Donald's boat
Conotrema urceolatum (Can-of-worms lichen) Description: It was glued to bark and I cannot peel off the bark on its underside. According to Ernie Brodo it's almost always sugar maple. I will check that out. My location: It was on a tree on the path.
Flavoparmelia caperata (common green shield lichen) Description: Green shield lichen, which Ernie Brodo confirmed, has wavy lines that seem quite characteristic. There seems to be two grey lichens associated with it on the bridge. One looks to be similar in size and shape to the green shield lichen and has rounded indented margins. The other has a narrow thallus and looks like it was a cut-out. ends are clipped straight, sides are curved.
My location: On the bridge
Graphis scripta Description: black squiggles on white patches on bark My location: trees along the path, mostly maple?
Leptogium saturninum (maybe) Description: "Black and white cup lichens". The concave aspect is black, the underside is white with a hint of orange at the edge that disappears in full sunlight. Small. My location: Growing on moss on rocks. along the road across the river.
Paremelia rudecta (rough speckled shield lichen) Description: browned edges and soralia in the middle, much like common green shield lichen My location: Bridge railing Paremelia squarrosa (bottle brush shield lichen) Description: burnt paper edges; has a concavity; rhizomes are black squarrose My location: Bridge railing
"Pelt lichen" My location: 2 growing near Donald's boat. I could not identify the species. Phaeophyscia ciliata (maybe) Description: There is a small rosette type, gray, very narrow lobes, under 1 mm I would say. I will look again to see if the rhizines stick outward to look like cilia. My location: Bridge floorboards
Porpidia albocerulescens (smoky-eye boulder lichen) Description: Black dots on a pink-brown thallus. Crustulose My location: boulder by the area where snow is piled
Xanthoria polycarpa (pincushion sunburst lichen) Description: yellow lichen with tiny lobes and yoke-yellow apothecial disks, lecorine. Other species: I went through all the foliose lichens in the big book. There seem to be only two general of yellow foliose lichens that are found in this area. Many more elsewhere. These are Candelaria (2 sp) and Xanthoria (5 sp). I think this is Xanthoria polycarpa (pincushion sunburst lichen). Smaller chance it is Xanthora hasseana My location: On a twig near the gazebo
Xanthoria somloensis (shingled rock shield) Description: My location: On boulder across the river on the road
Usnea hirta (shaggy beard lichen) Description: Ernie Brodo called the stringy green lichen I showed him from the bridge a "beard" lichen. Looking at Lichens of N America and the distribution and description of beard lichens, it looks like it must be Usnea hirta, bristly beard lichen (also shaggy beard lichen). However I will check the details out to see that they match. There is an associated lichen on the bridge which looks like thin steel wool. I am not sure what this is. My location: Bridge