An order of the Ascolichenes or of the Discomycetes in which the majority of *lichens
(8-10 000 species) are placed. Such lichens bear apothecia on their upper surface from which ascospores are violently discharged. The Lecanorales includes such genera as Cladonia, Lecanora, Parmelia, Umbilicaria, and Usnea. The fungal partners in such lichens are closely related to the *Helotiales
. In certain lichens, e.g. Sphaerocarpus species, the asci and paraphyses of the apothecium disintegrate at maturity to form a mass of spores and hymenial tissues. Such lichens may be placed in a separate order, Caliciales. In other lichens the apo-thecium may be locular and elongate and contain pseudoparaphyses rather than true paraphyses. Such lichens may be placed in the order Hysteriales. Rocella tinctorum, a lichen from which the dye litmus is obtained, is an example of this group.