Below are terms important in the identification of different lichen and understanding their morphology:
-Algae: Green photosynthetic organism that contains chloroplast, belonging to the Kingdom Protoctista
-Apothecia (-cium): A cup- or disk-shaped fruiting body, usually with the spore-bearing layer exposed
-Cilia: Hair-like structures on the edges of apothecia or thalli, usually found on foliose and fruticose lichens
-Cortex: The external protective layer of a lichen
-Crustose: A lichen type where the thallus is in close contact with the surface it resides on; attached completely and cannot be removed from the surface without damage to the lichen or the surface it is on
-Fibril: A short branch, perpendicular to the main filament. Seen in many Usnea
-Foliose: Considered "leafy" lichen that varies from tightly attached to the surface it is on to a single location where it holds fast to
-Fruticose: Lichen who have a thallus that is stalked, shrubby, or pendent. They do not usually have a distinguishable lower and upper surface
-Hyphae (-a): The filamentous element of the fungus, often resembling angular or round cells. Used to absorb nutrients from their environment
-Insidia (-dium): A small outgrowth on the lichen that has a cortex and contains photobiont cells. They are easily detached and serve as reproductive units
-Lobe: A rounded projection or division of a thallus, measured at its widest point
-Medulla: The internal layer in the thallus or apothecium, composed of hyphae and can vary in color but should not be confused with the photobiont (algal) layer
-Papillae: Small bumps on the outer surface of lichen that resemble "goose pimples" or "goosebumps"
-Pendent: A term used to describe a lichen that hangs straight down and is usually pliable and soft to the touch. Lichen can be almost pendent, where the base is bushy and stiff but the rest of the lichen hangs down
-Photobiont: The photosynthetic symbiont in a lichen that is either algae or cyanobacteria
-Podetia (-tium): A stalk formed by lower apothecial tissues which can have fruiting bodies present. Can be either unbranched or branched, varying in height
-Rhizine: Hyphal extensions of the lower cortex that attaches a foliose lichen to the surface it sits on. Rhizines can have varying lengths, colors, thickness, and types of branching
-Soralia (-lium): An area where the cortex is cracked or worn away and soredia are produced
-Soredia (-dium): A asexual reproductive unit that is generally produced in localized masses called soralia, or covering large areas on a thallus. Lacks a cortex
-Squamule: A small, scale-like lobe that lifts from the surface it sits on at the edges or can resemble an almost foliose structure
-Thallus: The vegetative body that consists of both fungal and algal components. Used to describe the main body of the lichen as a whole
-Umbilicate: A lichen that is attached by a central, single holding point on the lower surface of the thallus