The taxonomy of the group has seen numerous changes; it was formerly often treated as a suborder of the order Lecanorales.

[1][2][3] The fungi form lichens in a symbiotic relationship with one or two photosynthetic partners which may be a cyanobacterium such as Nostoc or a green alga such as Coccomyxa.

The thallus of the lichen may be foliose (leafy), subfruticose (somewhat shrubby) or granular-squamulose (scaly).

In some species, the thallus may vary in appearance depending on whether it contains a cyanobacterium or a green alga.

Members of the suborder Peltigerineae produce a wide range of secondary compounds, some of which are useful to humans in medicine and dyeing.