Crustose: Crusty lichens! Fully attached to the substrate. Usually can’t be removed without damaging the lichen and or the substrate.
Foliose: Leafy lichens! Flat, usually detached from the substrate at various points so that you can see the upper and lower thallus and remove them from their substrate.
Fruticose: Fluffy lichens! They have a tufted or stalked thallus, and it can be difficult to determine an upper and lower surface. Often look like little plants.
Squamulose: Scaly lichens! Thallus made up of small, flat, overlapping units. Not as attached as crustose lichens, but more attached than foliose lichens.
Thallus: The lichen body which contains both the fungal and photobiont (algal or cyanobacterial) components.
Cortex: The protective outer wall of the thallus made of specialized fungal hyphae. Lichens can have separate upper and lower cortexes, a wrap-around cortex, a single cortex, or no cortex.
Rhizines: Kinda like the roots of a lichen. Little filaments that protrude out of the bottom of the thallus and attach the lichen to the substrate.
Cilia: Stringy protrusions projecting from the sides or upper surface of the lichen. Different from rhizines.
Photobiont: The symbiotic component of the lichen that performs photosynthesis. An algae or a cyanobacteria.
Podetia: Hollow, stalk-like protrusions of Cladonia lichens
Apothecia (apothecium): A fruiting (sexually reproducing) structure produced by the fungal component of the lichen. Usually rounded cup which contains fungal spores. Not present on all lichens, but often help with identification. And are very cute.
Perithecium (pl. perithecia): An embedded, flask-shaped ascocarp (fruiting body) in the thallus that releases sexual fungal ascospores. Often only visible from the outside as a small hole or pore.
Isidia (isidium): Small thallus outgrowth that acts as an asexual propagule for lichens, and contain both fungal and algal constituents. They can detach and grow a whole new lichen clone! They have a cortex.
Soralia and Soredia: Soralia look like cracks in the lichen surface filled with powdery granules (the soredia). Soredia are another asexual propagule and include both mycobiont and photobiont constituents, and they lack a cortex.
Schizidia (schizidium): Scale-like asexual propagules. They have an upper cortex but no lower cortex.
Macula: small pale spot resulting from a lack of photobiont cells in that area of the thallus.
Pruina: Powdery deposit of crystalized calcium oxalate, secondary lichen metabolites, or dead fungal cells. Makes the surface of the lichen look frosty or chalky (adj. pruinose).
Cyphella: A recessed pore in the lower thallus surface with a pale rim where fungal hyphae poke through. Round, usually pale, fuzzy-looking spots.
Pseudocyphellium: A pore on the lichen thallus surface lacking cortex so medullary hyphae stick out. Lacks a defined rim, can be linear or orbicular.
Pycnidium (pl. pycnidia): An embedded, round or pear-shaped structure that goes down through the thallus and into the medulla and produces small spores that can either be asexual propagules or spermatia. Appears as a small, dark pore in the lichen surface.
Areolate: A crustose thallus growth form that appears tile-like in appearance. It looks like dried and cracked paint/clay. Each individual section is an areole.
Rimose: A crustose thallus growth form that has cracks, splits, or striations.
I will continue to edit and add more as needed!
