Gray Reindeer Lichen

IUCN Red List

not listed

NatureServe

NNR - Unranked
SNR - Unranked

Minnesota

not listed

Gray Reindeer Lichen is a common and widespread, slow growing, long-lived, shrubby lichen. It occurs around the globe in the Northern Hemisphere (circumpolar). In the United States, it occurs east of the Great Plains and in the Pacific Northwest. It is common in northeastern Minnesota.

Gray Reindeer Lichen is found in a variety of habitats, including sunny, exposed, relatively dry areas; open, relatively humid, coniferous forests; shrublands; and tundra. It is one of the most abundant lichens in tundra. It grows over rocks, on thin soil on the ground, and in moss in forested areas.

Gray Reindeer Lichen grows very slowly, on average just ⅛″ to ⅜″ (3 to 11 mm) per year. A 4″ (10 cm) mat may represent over half a century of steady growth. Growth is fastest – if that word can be used – in shadowy forests. In open exposed areas the growth rate is significantly slower. During dry spells growth essentially stops because it lacks roots and relies on the air for moisture. While individual stalks might decay at the base after 100 to 150 years, the colony itself can be much older, essentially "walking" across the landscape as the tips grow forward and the bases turn to humus.

The vegetative body (thallus) is a shrubby tuft of many branching stems. The primary thallus is inconspicuous and composed of scaly, flaky, rounded, prostrate pieces (squamulose). It is ephemeral and it is usually not visible. The secondary thallus is conspicuous, upright, three dimensional, and shrubby (fruticose). It is composed of numerous hollow stalks (podetia). The podetia are 2″ to 4¾″ (5 to 12 cm) tall, up to 1⁄32″ to 1⁄16″ (1.5 to 2 mm) thick, and three or four times branched. The surface is smooth or slightly cottony or cobweb-like (arachnoid), and it may be continuous or perforated. It is usually ash gray, rarely yellowish white. If snapped off, the interior wall of the hollow podetia is gray, black only at the absolute microscopic tip of the “foot” where it meets the dirt. The main axis of the podetia is paler toward the base, but with age it decays and blackens where it touches the moist soil, at most ⅜″ to ¾″ (1 to 2 cm) from the base.

Each branch ends in three or four short branchlets. The tips of the terminal branchlets are strongly bent in the same direction (unilaterally deflexed).

Disc- or cup-shaped reproductive structures (apothecia) are rarely produced. When present, they are at the tips of the branches, brown, and usually very small.

Similar Species

Black-footed Reindeer Lichen (Cladonia stygia) podetia appear “dirty gray” halfway up the base because the outer surface breaks up into irregular patches (areoles) exposing the inner coal black tissue. The surface is rough due to the areoles.

Green Reindeer Lichen (Cladonia mitis) usually has a yellowish or pale green tint because it contains usnic acid, which the Gray Reindeer Lichen lacks. The terminal branchlets spread in all directions.

Substrate

Thin soil, rocks, moss

Growth Form

Fruticose

Habitat

Sunny, exposed, relatively dry areas; open, relatively humid, coniferous forests; shrublands; and tundra.

Hosts