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!