Xanthomendoza oregana
Xanthomendoza oregana is a bark-dwelling lichen in the Teloschistaceae family. It forms a bright yellow to orange tufted patch (thallus) up to about 3 cm across. The leaf-like lobes lie flat against the tree surface but can lift slightly, and the upper surface is smooth or slightly wrinkled. Margins often have small structures called blastidia for asexual reproduction, and the underside can have scattered rhizines. Apothecia (fruiting bodies) are not common, but when they do occur, they can be numerous; pycnidia are common and produce conidia that range from ellipsoid to rod-shaped. The lichen’s chemistry fits chemosyndrome A.
Distribution and habitat: Xanthomendoza oregana grows on deciduous trees in lowland temperate areas. In southern Sweden it’s often found in parks and churchyards, indicating a preference for light and good air flow. It occurs in western Europe and western North America, where it is especially widespread in the Pacific region.
Taxonomic history: The species was first described in 1932 by Vilmos Gyelnik as Xanthoria oregana from a specimen collected in Corvallis, Oregon on maple. In 2003, it was moved to the genus Xanthomendoza by Søchting, Kärnefelt and Kondratyuk. It has also been placed in Oxneria and Gallowayella in the past, but those names are not widely used. Xanthomendoza poeltii, described in 1997, is now considered the same species after DNA work.
Similar species: X. oregana is typically smaller with narrower lobes and a thinner upper cortex than Gallowayella fulva, and it lacks the rosette-like thallus of Xanthoria ulophyllodes. It also tends to have edge-based soredia rather than the bird-nest-like tips seen in some other species.
This page was last edited on 3 February 2026, at 20:25 (CET).