Freckled Pelt Lichen

Description

There are about 100 lichen species in the genus Peltigera. Most contain a single fungal partner (mycobiont) and a single photosynthetic partner (photobiont), either an alga, almost always a green alga, or a cyanobacteria. Only a handful, including Freckled Pelt Lichen, are tripartite, containing two photosynthetic partners: a green alga, producing most of the food, and a cyanobacteria, providing essential nitrogen.

Freckled Pelt Lichen is a large, common and widespread lichen. It occurs throughout the temperate and boreal regions of the Northern Hemisphere (circumpolar). In the United States it occurs in the east from Maine to New York, west to Minnesota, and south along the Appalachian Mountains to northern Georgia. In the west it occurs from Washington and Oregon, west to Montana, south along the Rocky Mountains to northern New Mexico, and south along the Cascade Range and Sierra Nevada Range to northern California. It occurs throughout Canada and Alaska.

Freckled Pelt Lichen is found in open and closed northern boreal forests, open subarctic forests, bogs, tundra, and on the slopes of mountains. It grows on land-dwelling (tericolous) mosses, clay, and turf, on soil that is rich in decomposed plant material (humus), and on dead leaves.

The vegetative body (thallus) is leaf-like (foliose). It forms a large rosette that is often up to 6″ to 9½″ (15 to 24 cm) in diameter, sometimes more than 3′ (1 m) in diameter. The lobes are usually concave to boat-shaped with the margins turned upward. They are usually ⅜″ to ¾″ (1.5 to 4 cm) wide, sometimes wider, and up to 4″ (10 cm) long, sometimes longer. The lobes branch sparingly, and adjacent lobes touch but are not fused together.

The upper surface is hairless, bright green when wet or moist, and pale grayish green to brownish green when dry. It is freckled with scattered dark gray to grayish brown, up to 1⁄16″ (2 mm) wide, flattened, wart-like growths (cephalodia). The cephalodia contain the cyanobacteria (Nostoc) while the rest of the thallus contains the mycobiont and the other photobiont. Special, thick-walled cells (heterocysts) in the filaments of the Nostoc capture atmospheric nitrogen from the air and convert it into usable nitrates.

The lower surface of the thallus is mostly black to brown, abruptly turning white at the upturned margins. It does not have an outer protective layer (cortex). Instead, it has a network of broad, indistinct veins, and it is held to the substrate by a few dark, up to 3⁄16″ (5 mm) long, root-like structures (rhizines). The rhizines may be unbranched, or sometimes two or more rhizines appear to rise from a single point (fasciculate).

Sexual (spore-producing) reproductive structures (apothecia) on the margins of the thallus are common and large. The apothecia are ¼″ to ⅝″ (7 to 15 mm) wide, oblong to more or less round, and curved inward, appearing saddle shaped. The disc is flat, smooth, and reddish brown. The back appears more or less uniform, not patchy.

Similar Species

Ruffled Freckled Pelt Lichen (Peltigera leucophlebia) is similar, but the lobe margins are distinctly ruffled, and the back of the apothecia appear patchy.

Ecology

Substrate

Ground

Growth Form

Foliose

Habitat

Boreal forests and mountain slopes

Hosts