About Xanthoparmelia stenophylla (Ach.) Ahti & D.Hawksw.
Xanthoparmelia stenophylla is a foliose lichen species belonging to the family Parmeliaceae. This lichen contains usnic acid, which gives its upper cortex a yellowish look, although its overall colour can vary substantially depending on environmental conditions. Research has found that when exposed to ultraviolet radiation (UVR), Xanthoparmelia stenophylla develops a unique dull blue pigment in its cortex. This pigment acts as a protective barrier against photoinhibition in habitats with high levels of light. The UVR-induced blue pigmentation, which has been observed to develop within 21 days of UVR exposure, is insoluble in acetone and similar to melanin compounds that occur in other lichens. The capacity to produce this protective pigment may help X. stenophylla thrive in sun-exposed habitats. When kept shielded from UVR, the lichen retains its characteristic pale-green colour. Xanthoparmelia stenophylla is a documented host for the lichenicolous fungus Lichenostigma cosmopolites.
