Cladoniaceae

The Cladoniaceae are a family of lichen-forming fungi in the order Lecanorales, comprising about 560 species distributed amongst 18 genera. This family is one of the largest among lichen-forming fungi and is globally distributed, from Arctic tundra to tropical rainforests, favouring humid environments while being intolerant of arid conditions. Notable members include reindeer moss and cup lichens of the genus Cladonia, which consist of about 500 species and forms a significant part of the diet for large mammals in taiga and tundra ecosystems.
A distinctive feature of many Cladoniaceae species is their dimorphic thallus: a scaly or crust-like primary form and a fruticose (shrub-like) secondary form known as a podetium or pseudopodetium. These lichens typically grow on soil, decaying wood, or tree trunks, with a few species found on rocks. They form symbiotic associations with green algae, usually from the genus Asterochloris. Cladoniaceae species have been recorded growing in many habitats and on a diversity of substrates, including soil, tree trunks, and rotten wood. Cladoniaceae species are generally absent from arid environments due to their preference for humid conditions. Read more on Wikipedia.