About Parmotrema reticulatum (Taylor) M.Choisy
Parmotrema reticulatum, commonly called the Black Sheet Lichen, is a foliose lichen. Its grayish thalli grow from closely attached to loosely attached to their substrate. The thalli have prominent lobes made of slightly overlapping, rounded lobes that become more jagged as the lichen ages. Blackened areas frequently form on the upper surface of the thalli. The lower surfaces of the thalli are black, with brown mottled zones along the edges; root-like rhizines grow from the lower surface. Bowl-shaped reproductive structures called apothecia are rare; when present, they are small, reaching a maximum diameter of 6mm, and develop indistinct stalks. Verifiable observations of Parmotrema reticulatum recorded on iNaturalist show the species occurs worldwide in warm to hot climates, and is absent from tropical rainforests and arid areas. Parmotrema reticulatum most often grows on trees in open habitats, and rarely grows on rocks. In the Himalayas, this lichen is documented as a traditional treatment for coughs, throat issues, and respiratory problems. In Mexico, a tea made from the lichen is used to treat kidney disorders and venereal disease; this tea is prepared in the late afternoon and drunk the next morning. A methanol extract of Parmotrema reticulatum has been identified as a promising candidate for breast cancer management.
