Cladoniaceae

Cladoniaceae is a diverse and widespread family of lichens best known for the genus Cladonia, which includes many of the most familiar ground- and wood-dwelling lichens in temperate and boreal regions. Members of this family are especially notable for their two-part thallus structure, combining a basal layer with upright, often highly distinctive reproductive stalks.

Species in this family play important ecological roles in forest floors, decaying wood, and nutrient-poor substrates, where they contribute to soil formation and nutrient cycling.

Growth Form and Thallus

Cladoniaceae lichens typically exhibit a dimorphic thallus, consisting of:

A basal squamulose thallus made up of small, scale-like lobes
Upright podetia, which are stalk-like structures that bear reproductive features

The podetia may be:

Slender and pointed
Cup-shaped (forming “pixie cups”)
Branched or antler-like in some species

The basal squamules often persist at the base, though in some species they may be reduced or ephemeral.

Reproductive Structures

Reproduction in Cladoniaceae commonly occurs via:

Apothecia, often brightly colored (red, brown, or tan), located at the tips or margins of podetia
Vegetative propagules, such as soredia or fragments of squamules

Some species produce conspicuous red apothecia, while others reproduce primarily through vegetative means.

Substrate and Habitat

Members of Cladoniaceae are typically found on:

Decaying wood, including logs and stumps
Organic soil, especially in open or disturbed areas
Mossy substrates and humus-rich forest floors

They are especially common in acidic, nutrient-poor environments, where competition from vascular plants is reduced.

Identification Notes

Key features useful for identifying members of Cladoniaceae include:

Presence of podetia rising from a basal squamulose thallus
Podetial shape (cup-shaped, pointed, branched)
Color and placement of apothecia
Substrate preference (wood vs. soil)

Because of morphological diversity within the family, species-level identification often requires close inspection of podetial form and reproductive structures.

Ecology and Notes

Cladoniaceae lichens are important pioneer species, often among the first organisms to colonize bare or disturbed substrates. Some species form extensive ground mats that influence moisture retention and microhabitat structure.

Several members of the family are ecologically significant as forage for wildlife, particularly in northern ecosystems, while others are indicators of forest continuity and habitat quality.

Representative Genera

Cladonia — the largest and most recognizable genus in the family
Pilophorus — small, dark, stalked lichens of moist habitats
Stereocaulon — fruticose lichens with granular surfaces and shrubby forms

References

Brodo, I. M., Sharnoff, S. D., & Sharnoff, S. (2001). Lichens of North America
Consortium of Lichen Herbaria
Minnesota Seasons