The order Lichinales is a group of mostly lichen-forming fungi within the phylum Ascomycota. Members of this order are primarily lichenized, meaning they form symbiotic relationships with photosynthetic organisms, typically cyanobacteria, to create lichens. Lichinales are often found in extreme or nutrient-poor environments, such as deserts, rocky surfaces, and arid regions, where few other organisms can survive. Morphologically, they exhibit a range of thallus forms, from crustose (crust-like) to filamentous structures, and are characterized by their simple reproductive structures, producing small, usually single-celled ascospores. This order is considered ecologically important for soil stabilization, nutrient cycling, and as pioneers in colonizing harsh habitats.