Life habit: lichenized Thallus: foliose to umbilicate, irregularly coalescing and spreading extensively over its substrate, loosely attached, lobate lobes: usually convex, discrete, elongate, erect or semi-erect, eciliate upper surface: pale yellow to reddish orange, sometimes greenish yellow, smooth to somewhat wrinkled, often with pruina, lacking pseudocyphellae, with or without sorediate upper cortex: paraplectenchymatous medulla: white, reticulate with hyphae bundles; primary photobiont a Trebouxia sp., secondary photobiont lacking lower cortex: prosoplectenchymatous or paraplechtenchymatous lower surface: grayish white, with rhizines or rarely umbilicate holdfast; rhizines: simple Ascomata: apothecial, zeorine, laminal, sessile to stipitate; margin: concolorous with the thallus, smooth, with or without projections (cilia); disc: darker orange than the thallus or concolorous, eperforate; epihymenium: pale orange hymenium: usually hyaline below but light orange above; hypothecium: hyaline; paraphyses: simple or branched, sometimes anastomosing below asci: clavate to broadly clavate, 8-spored, Teloschistes-type (sensu Honegger 1978) ascospores: broadly ellipsoid to oblong, polarilocular, hyaline, 10-20 x 5-8 µm; septum: narrow to wide, 4-6 µm Conidiomata: pycnidial, concolorous with the thallus or darker, immersed conidia: simple, bacilliform, hyaline Secondary metabolites: anthraquinones present in colored parts Geography: world-wide Substrate: on bark and rock, rarely on soil or other substrates. Notes: The majority of the taxa of Xanthomendoza were until recently included in the genus Xanthoria (the 'Xanthoria fallax group', or, 'Xanthoria ulophyllodes group'). Morphological and molecular studies have shown that these two groups form a separate lineage (Arup and Grube 1999), and, according to Søchting et al. (2002), it deserves genus rank. Morphologically and chemically the genus is similar to Xanthoria, but differs mainly by having bacilliform conidia and well developed rhizines. If apothecia are present, the thalline margins frequently develop rhizinelike projections, here termed cilia.