Rhizocarpaceales

Rhizocarpaceales is an order of lichen-forming fungi within the class Lecanoromycetes. This order primarily contains crustose lichens, meaning they form a tightly adhering, crust-like thallus on their substrate. Members of Rhizocarpaceales are found globally and colonize a variety of substrates, including rocks, soil, and bark.

The order is characterized by specific reproductive structures. The apothecia, which are the fruiting bodies, are typically lecideine, meaning they lack a distinct exciple. The asci, the spore-bearing cells, are unitunicate and contain eight ascospores. These ascospores are usually hyaline, simple (unsegmented), and ellipsoid to broadly ellipsoid.

A notable genus within Rhizocarpaceales is Rhizocarpon, which gives the order its name. Species within Rhizocarpon are often referred to as "map lichens" due to the appearance of their often areolate (divided into small sections) thalli. These lichens are known for their slow growth and longevity, and some species are used in geological dating methods due to their predictable growth rates. Other genera within the order include Bellemomera and Amygdalaria, though Rhizocarpon is the most extensively studied and contains the majority of recognized species. The exact phylogenetic placement and circumscription of Rhizocarpaceales have been subject to revision with advancements in molecular phylogenetic studies.