The genus includes about 50 recognised species, which exhibit a variety of growth forms ranging from flat and crust-like to more complex, leaf-like structures.

Peltula lichens play important ecological roles in harsh environments, contributing to soil stability and nutrient cycling.

The genus has a cosmopolitan distribution, with members found across various continents, occupying diverse substrates including rocks, soil, and occasionally tree bark.

In his original description of Peltula radicata, Nylander characterised it as having a rust-brown, peltate thallus measuring at least 3 mm wide, with an irregularly and sparsely grooved surface.

He noted that the thallus had a centrally depressed, umbilicate attachment, fixed to the substrate by a few pale, long, and strong rhizines.

Nylander described the apothecia as disc-shaped and the same colour as the thallus, initially almost endocarpoid, but expanding significantly with age and featuring a depressed thalline margin.

deserticola P. congregata P. umbilicata P. coriacea P. rodriguesii P. farinosa Neoheppia brasiliensis P. leptophylla Phyllopeltula corticola P. obscurans var.

hassei P. michoacanensis P. imbricata P. inversa P. capensis P. boletiformis Neoheppia cataractae P. euploca P. omphaliza P. sonorensis P. bolanderi P. psammophila P. radicata P. patellata P. richardsii P. africana P. obscuratula Lichinella Egea (1989) and Büdel (1987) made early attempts to establish phylogenetic lineages within Peltula based on morphology.

Traditional morphological characters, such as growth forms and thallus anatomy, which were previously used to delimit genera and species within the family, have been shown to be unreliable indicators of phylogenetic relationships.

[17] In North America, the colloquial name "rock olives" refers to members of this genus, highlighting both their colour and typical substrate.

[19] The family is characterised by uniform reproductive structures across all species, including polysporous asci with a distinctive gelatinous sheath, and simple, single-celled, colourless spores.

[19] Pycnidia, conidiophores, and pycnospores are also consistent in structure throughout the family;[15] the conidia are hyaline, oval to fusiform in shape, and have dimensions of 1.5–4.3 by 0.5–2.5 μm.

An exception is Peltula langei, which produces a yellow pigment similar to myeloconon C.[15] The thallus structure of Peltulaceae species shows various adaptations to their predominantly arid and semi-arid habitats.

These morphological and anatomical features reflect the family's successful adaptation to challenging environmental conditions, allowing them to grow in a range of ecological niches from desert rocks to occasionally submerged surfaces.

Despite their preference for dry habitats, some species have been documented in areas with more moderate climates, including locations as far north as Sweden and as easterly as the Baikal region of Siberia.

A 2024 study in northeastern Brazil found that P. obscurans, P. euploca, and P. impressa were able to colonise rocks with high levels of natural gamma radiation, while most other lichen genera were absent from these uranium-rich substrates.

Under constant sun exposure for most of the day, the lichens develop a thickened upper cortex that both helps to retain moisture and acts as a photoprotectant.

Certain Peltulaceae species have developed the ability to withstand periodic inundation, allowing them to inhabit seepage areas on rocks that are occasionally flooded.

Species that experience occasional submersion often possess large medullary cavities, an adaptation that likely aids in gas exchange and water relations during both dry and inundated periods.

[15] As primary producers in often-sparse environments, they contribute to soil stability, nutrient cycling, and provide microhabitats for other organisms, playing a role in the biodiversity of challenging climatic regions.