Freckle Pelt Lichen Identification Guide

First Impressions and Where You Are Standing

The Freckle Pelt is a lichen rather than a mushroom, and finding it means changing your search image. You will typically be in cool, damp, northern or montane forest, on a bank of deep moss beneath spruce, pine or birch, or out on tundra and heath among dwarf shrubs. It also spreads over mossy boulders, old logs and the humus of shaded roadside cuttings. The clue that brings you to a stop is a large, loose sheet of vivid, almost apple-green tissue lying on the moss like a discarded piece of soft leather, four to twenty centimetres across, with broad rounded lobes lifting slightly at the edges.

Look closer and the second, decisive feature appears: the green surface is scattered with dark, wart-like bumps, brown to blackish, one to three millimetres across, sitting on top of the lobes like freckles or crumbs. That combination, bright green foliose thallus plus dark superficial warts, is the identification in a single glance, and everything that follows is confirmation.

Reading the Upper Surface

Handle the thallus dry and then wet, because the colour depends entirely on water content. Dry, it is a dull grey-green, greenish-grey or almost drab olive, stiff and slightly brittle, and it curls at the margins. Splash it with water and within seconds it turns soft, pliable and a startling bright green. This dramatic wetting response is worth carrying a water bottle for; it is a genuine field test.

The lobes are broad, rounded, up to two or three centimetres wide, with entire to shallowly notched, sometimes slightly wavy or ascending margins. The surface is smooth to faintly wrinkled, matt rather than shiny, and usually hairless in the centre although the young lobe tips may be minutely downy.

Now examine the freckles properly with a hand lens. These are cephalodia, small discrete packets of a different partner organism sitting on the upper surface. They are roughly circular to irregular, convex, warty or slightly coralloid, dark brown to blackish-grey, and they can be scraped off with a fingernail to leave a paler scar. Crucially, they sit on the surface rather than being embedded within the thallus. Their density varies: some thalli are peppered, others carry only a handful near the lobe centres.

The Lower Surface

Flip a lobe over. This is where many pelt lichens are actually identified.

The underside is pale, whitish to cream or buff towards the margins, becoming darker brown only in the oldest central parts. It is covered in a soft, felty tomentum, and running through it are conspicuous raised veins that branch and anastomose into a coarse network. Between the veins the surface is paler and slightly hollowed. In the Freckle Pelt the veins are broad, low and only weakly contrasting, blending into the pale interspaces rather than standing out as sharp dark cords.

From the veins arise rhizines: tufts of pale, simple to slightly branched anchoring strands, scattered rather than dense, which hold the thallus loosely to the moss below. The whole lichen can usually be peeled up intact with a little of the moss attached.

Fruiting Bodies and the Question of a Spore Print

Because this is a lichen, the usual spore-print routine does not apply, and a guide that promised one would mislead you. The fungal partner instead produces apothecia: reddish-brown to chestnut discs borne on short, erect extensions at the tips of the lobes, often folded into a saddle or curled into a vertical, tongue-like flap, three to twelve millimetres across. When present they are conspicuous, standing up above the flat thallus like small brown flags.

If you want the spores, the practical method is to cut a thin section of an apothecium, or to invert a fresh apothecium over a glass slide in a humid chamber overnight and examine the deposit under a microscope. The spores are colourless, long and needle-like, several times longer than wide and divided into several cells by cross-walls. There is no visible bulk deposit of colour to read with the naked eye, so the fruiting body itself, not a print, is the character you record.

Internal Structure and Colour Change

Slice a lobe cleanly with a razor. In section you see a thin upper fungal skin, then a bright green algal layer, then a loose white fungal medulla, then the felty lower surface. That green band is the primary photosynthetic partner, a green alga, and it is what makes the lichen turn brilliant green when wet. The dark cephalodia, sectioned separately, contain a different partner, a blue-green cyanobacterium, packed in dark clumps.

Cutting produces no colour change in the ordinary sense. The medulla stays white; there is no latex, no bruising reaction, and handling merely darkens damp tissue slightly.

Substrate, Season and Ecology

The Freckle Pelt is a ground lichen of cool, humid, low-pollution habitats: boreal and montane conifer forest, birch woodland, arctic and alpine tundra, mossy heath, shaded banks and mossy rock ledges. It requires a moss carpet or a soft humus surface to spread over and cannot compete on bare mineral soil or on dry, sun-baked rock.

Unlike a mushroom it is present all year, so there is no season for finding the thallus, only better and worse conditions for seeing it at its best: wet weather makes it green and obvious, dry weather makes it grey and easy to walk past. Apothecia are most often produced in late summer and autumn. Because it grows very slowly and is easily torn from its moss, it is a good indicator of long-undisturbed ground.

Separating It from Look-Alikes

Peltigera leucophlebia is the closest match, also bright green when wet and also bearing cephalodia. Turn it over: its lower surface has strongly contrasting, dark, sharply raised veins standing out against distinctly pale interspaces, giving a bold network, whereas the Freckle Pelt has broad, low, weakly contrasting veins on a generally pale underside.

Peltigera britannica shares the green thallus but its cephalodia are embedded within the thallus, appearing as flattened, paler swellings that can pop out and leave a hole, rather than sitting as discrete dark warts on top.

Dog Lichen (Peltigera canina) and its relatives never turn bright green when wetted, because their only partner is a cyanobacterium; they stay grey-brown to dull lead-grey, and they lack cephalodia entirely while usually having a densely woolly upper surface and long shaggy rhizines.

Arctic Kidney Lichen (Nephroma arcticum) is also large and bright yellow-green but has a smooth, hairless, dark lower surface without a raised vein network, and it carries its brown apothecia on the underside of upturned lobe tips.

Lobaria species are ridged and pitted into a net-like relief on the upper surface, quite unlike the smooth lobes of the Freckle Pelt.

Keep the checklist short: broad green-when-wet lobes, dark superficial warts on top, a pale felty underside with low branching veins and scattered pale rhizines, and brown saddle-shaped discs at the lobe tips, all sitting on moss in cool northern woodland.