Lichen Terminology

Apothecia
Cup- or disk-shaped fruiting bodies where fungal spores (ascospores) are produced.

Ascospore
Sexual fungal spore released from the apothecia.

Conidia
Asexual fungal spores formed in specialized structures, often tiny black dots on the thallus.

Cortex
A protective outer fungal layer covering the upper (and sometimes lower) surface of the thallus.

Crustose
Growth form tightly attached to the substrate; cannot be removed without damage.

Cyanobacteria
Blue-green photobionts capable of nitrogen fixation; present in some lichens (cyanolichens).

Endolithic
Growing partially or fully within rock or mineral substrate.

Epiphyte
Growing on plants (often tree bark) without drawing nutrients from the host.

Fruticose
Branching, shrub-like or hair-like lichens with three-dimensional structure.

Foliose
Leaf-like lichens with distinct lobes and a lower surface.

Leprose
Powdery lichens lacking differentiation into distinct layers.

Lobe
Flattened or elongated projections of foliose lichens.

Medulla
The loose fungal layer beneath the cortex where nutrient and water retention occur.

Metabolites (Secondary Metabolites)
Chemical compounds produced by lichens for protection — responsible for many lichen colors.

Pycnidia
Minute flask-shaped structures producing conidia; appear as tiny dark dots.

Soredia
Powdery reproductive granules containing fungal hyphae + photobiont cells.

Thallus
The entire body of the lichen.