Lichens of the Macoun Field Club’s nature study area in Ottawa, with comments
Physconia to Xanthoria
Click here to return to the first third of the list: Acarospora to Dermatocarpon and here for the middle section:Dimerella to Physciella
Frost Lichens | Physconia detersa | A grey to brown foliose lichen with frosted lobe tips, growing on tree trunks. It is very common in southern Ontario. | |
P. leucoleiptes | A grey foliose lichen with crescent-shaped soralia on the tips of short lobes. We have found it three times, once on Pascal’s White Ash sapling, in open sunshine, once on a White Cedar in a shady pine forest, and once on a block of limestone in a forest (the “tombstone”). It is probably frequent in southern Ontario, under the name P. perisidiosa, which is actually a western species. | ||
Tar-spot Lichens | Placynthiella uliginosa | A crust composed of greenish or brownish, rounded granules (0.1 mm across) massed together on soil, with very small black disks sometimes abundant. It binds loose, sandy soil in a way that prevents erosion. We found it fringing a patch of moss that is growing out over bare sandstone. It is considered frequent in the Ottawa region, but rare in southern Ontario. (Our specimen is odd in having a colourless, rather than dark brown hypothecium.) | |
Ink Lichens | Placynthium nigrum | A crustose lichen that looks like an ink stain on limestone rocks. Often there is a bluish black line around the edges. It is common in southern Ontario. | |
Black Bump Lichens | Polyblastia sp. | No easy fit with known species. That isn’t saying much, because the whole genus, which is mainly Arctic in distribution, is poorly known. Our specimen is on the underside of a noncalcareous, fingernail-sized sandstone pebble from an expanse of bare sandstone. It is a dark greenish crust with a few truly minute black bumps, inside of which are multi-celled spores. Whatever it is, it is new to the province of Ontario. | |
Coal-Dust Lichens | Polysporina simplex | Tiny black spots, often clustered together along cracks in rocks other than limestone. The rest of the lichen, the part with algae, lives inside the rock, bewteen the crystals. Under magnification, the spots look like wrinkled prunes. It is frequent in southern Ontario. | |
Boulder Lichens | Porpidia albocaerulescens | ![]() |
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P. crustulata | ![]() |
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Speckled Shield Lichens | Punctelia bolliana | ![]() |
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P. caseana | Specimen found on Eastern White Cedar in a moist forest. New to southern Ontario. | ||
P. rudecta | An olive-green foliose lichen on trees and rocks. The lobes have many tiny white spots, and the center of large patches of thee lichen are rough and dark with abundant minute projections (isidia). It forms large patches on forest trees in the Study Area, and it is very common in southern Ontario. | ||
Pox Lichens | Pyrenula pseudobufonia | A crustose lichen that makes pale olive stains on the smooth bark of Beeches and other trees. Scattered black bumps that are relatively large (close to 1 mm wide) often emerge from within the bark. We have found it only once, on a Beech tree recently chosen by Madeleine. It is considered frequent in southern Ontario. | |
Pyxine sorediata | ![]() |
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Ramalina | Ramalina americana | A shrubby lichen with flattened, yellowish green branches and yellowish green disks at the tips. Since Loney Dickson reported it in 1972, we have found it only three times, always on Butternut trees, but in very different habitats (a clearing, and a swamp). It is common in southern Ontario. | |
R. intermedia | Another shrubby lichen, but with tiny elliptical powdery patches on the flattened, yellowish green branches. We recently (2007) found a cluster of a dozen tufts of it on the trunk of an ash tree in a swamp. It, too, is common in southern Ontario. | ||
Map Lichens | Rhizocarpon grande | ![]() ![]() |
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R. lecanorinum | ![]() ![]() Our specimen was observed and photographed repeatedly, but not collected. It was about 6 mm across in 2003 (above left), and and had grown to 9 or 10 mm as of 2007 (same scale, at right). But at that point it had lost the central area and become a broken ring.
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R. obscuratum
(R. reductum) |
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R. submodestum | ![]() |
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Rock-posy Lichens | Rhizoplaca subdiscrepans | A thick, lumpy, slightly greenish-grey lichen on granite rocks, with large, pale orangish disks. We found it on a large glacial erratic boulder in full sunshine. It is considered frequent in the Ottawa region, but rare across southern Ontario. | |
Pepper Spore Lichens | Rinodina destituta | ![]() |
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R. freyi | ![]() |
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R. subminuta | ![]() |
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Comet-spored Lichens | Ropalospora viridis | Specimen found on maple in a moist forest. New to southern Ontario. | |
Dimple “Lichens” | Sarae resinae | Pale pinkish orange disks occuring on hardened conifer resin. It is not quite a lichen, because it does not make a partnership with algae, but it is close, and therefore of interest to lichenologists. We found it twice on dead conifers, and once on the old resin of a live one. | |
Grain-spored Lichens | Sarcogyne clavus | ![]() |
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S. privigna
(S. hypophaea) |
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S. regularis | Pale bluish grey disks on limestone. The apparent colour comes from a dusting of reflective crystals that conceal the disk’s true reddish brown underneath. Frequent in the Ottawa region. | ||
Dot Lichens (genus Scoliciosporum) | Scoliciosporum chlorococcum | Tiny black dots on a granular green crust. We find it on dead conifers, both low and high in the trees, on mainly on branches. It is one of the most common bark-dwelling crustose lichens of southern Ontario. | |
S. umbrinum | ![]() |
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Stubble “lichen” | Stenocybe major | Tiny stalks (less than 1 mm long) with knobs on the end, growing only on the smooth bark of Balsam Fir trees. Not a lichen, because there are no algae associated with it. It occurs occasionally on firs in the Ottawa region, and is sparse (and hard to see!) on any given tree. | |
S. pullatula | Tiny (0.3 mm high) black stalks on alder bark. It is new to the Ottawa region. | ||
Foam Lichens | Stereocaulon saxatile | ![]() |
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Dot Lichens (genus Strangospora) | Strangospora moriformis | ![]() |
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Black Bump Lichens (genus Strigula) | Strigula jamesii | Specimen found on an Eastern White Cedar in a moist forest. | |
S. stigmatella | A greenish gray crust over mosses, with tiny black bumps that are perithecia (enclosed fruiting bodies). It is rare in Ottawa and in southern Ontario. | ||
Stone Lichens | Trapelia involuta
(T. glebulosa) |
A white crustose lichen with very small, dark disks. We have found it only in tiny, scattered bits on calcareous stone along the old railway rock cut in the north. It is very rare in southern Ontario, but not uncommon elsewhere in eastern North America. | |
T. obtegens | A crustose lichen; specimen found on a rock in a moist forest. Newly identified in southern Ontario. | ||
T. placodioides | A white crust with minute patches of faintly green powder, growing on calcareous rock. The edges are somewhat lobed. It is common in southern Ontario. | ||
Board Lichens | Trapeliopsis flexuosa | A minutely bumpy grey crust on the remains of an old, weathered fence rail. It is frequent in southern Ontario. | |
T. granulosa | A granular greenish or grey crust on sunny soil or old wood, often with hemispherical pinkish or lead-grey disks. We have found small amounts of it in both situations. It is common in southern Ontario. | ||
Speckled Blister Lichens | Trypethelium virens
(Viridothelium virens) |
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Ruffle Lichens | Tuckermanopsis ciliaris | Formerly Cetraria ciliaris. A dark brown foliose lichen with a very ruffled appearance, growing on conifer twigs. We find it on Jack Pine branches. Common in southern Ontario. | |
Beard Lichens | Usnea hirta | ![]() |
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U. subfloridana | Yellowish green tufts on conifer twigs. It differs from U. hirta in that the base of the stem is blackened, and that the main stems are roughened with minute patches of soredia. Frequent in the Ottawa region, rare in southern Ontario. | ||
Speck Lichens | Verrucaria calkinsiana | Black dots on a limestone slab in a maple forest. It is infrequent in the Ottawa region. | |
V. muralis | A white stain on limestone, speckled with black dots. It is infrequent in the Ottawa region. | ||
V. nigroscentoides | Tiny black dots on stone. We have found it twice, once on a piece of limestone long ago dug up by a woodchuck, now on the ground in a maple forest. The other time was on a limestone boulder in a different maple forest. It is rare in the Ottawa region, but frequent across southern Ontario. | ||
Rock-shield Lichens | Xanthoparmelia conspersa | A pale yellowish green, foliose lichen that is black beneath. We have found it only once, on sandstone. It is infrequent in southern Ontario. | |
X. cumberlandii | A medium-sized yellowish green lichen with a smooth upper surface, and a pale or brown lower surface. It is common in southern Ontario. We find it on granite boulders and sandstone bedrock. | ||
X. plittii | ![]() |
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X. stenophylla
(likely X. viriduloumbrina) |
This species is like the other Rock-shield Lichens, but with narrower lobes. It is common in southern Ontario.
For many years now, it has been known as Xanthoparmelia somloensis, but in the summer of 2005 the strict application of obscure rules of nomenclature showed that name to be incorrect. (By 2019, it has been changed again.) |
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Sunburst Lichens | Xanthoria elegans
(Rusavskia elegans) |
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X. fallax
(Xanthomendoza fallax) |
This is the lichen that turns roadside tree trunks orange. It is very common in southern Ontario, but not so much in our Study Area, which is mostly forest, and shady.
This species has been transferred to a new genus, Xanthomendoza. |
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X. hasseana | A small, orange foliose lichen with orange disks. We find it on the branches of deciduous trees in sunny places in our Study Area, and on one granite boulder in full sunshine. | ||
X. sorediata
(Rusavskia sorediata) |
A small orange, foliose lichen on rock, roughened in the older portions by tiny bumps that break into powdery soredia. It is rare in southern Ontario, and new to the Ottawa region. | ||
X. polycarpa | Frequent in southern Ontario. | ||
X. ulophyllodes | ![]() This species has been transferred from the genus Xanthoria to Xanthomendoza since Irwin Brodo’s Lichens of North America was first published. |
Click here to return to the first third of the list: Acarospora to Dermatocarpon and here for the middle section, Dimerella to Physciella
Return to Study Area introduction
All photos donated or provided by members, leaders, and friends, past and present. Created June 2002 by Macoun Club leader Robert E. Lee. Additions and new photos occasionally, most recently on July 9, 2011. Coding revised in May and June, 2016. Name changes added in March 2019.