Types of Lichens

Types of Lichens
Lichen Growth Forms
Crustose (crusty)
edges flat, unlobed and closely attached to substrate
hard to remove without damaging substrate or lichen
algae usually dispersed
edges unlobed (leprose and squamulose included here)
Foliose (leafy)
A sandwich of fungal layer with algal mat in middle
circular growth, lobes
small rootlets called rhizines attach it to substrate
top and bottom layers different
Fructicose (shrubby)
round branches with its fungal layer outside, its algal layer within
no rhizines
vertical growth pattern
odd-shaped structures such as globets; threads
Fruticose lichens are either shrub-like small mounds, growing up from the ground, or beard-like, small
tangles looking a bit like spanish moss when hanging down, attached to the substrate only at their
bases, and usually with a circular cross-section.
In addition, Leprose lichens are powdery masses with little or no organized structure; Squamulose are
much the same as crustose, but have raised edges, which can be folded and lobe-like.
All but fruticose lichens grow slowly; their growth, about .5 to 5 mm per year measured by the
expansion of their circles. Fruticose lichens, on the other hand grow vertically, and quickly, up to 2 cm
per year. Left unchallenged, undisturbed and with a suitably long-lived substrate, it is quite common for
a lichen to have a lifespan of several centuries; in fact a certain arctic specimen of a crustose lichen,
Rhisocarpon geographicum, was found to be about 9000 years old!