Parmotrema

Parmotrema is characterized by its typically large, moderately to loosely-attached foliose thallus with broad lobes that are usually more than 5 mm wide. There is a broad, naked zone around the margin of the lower surface, an epicortex with pores and an upper cortex with a palisade-plectenchymatous arrangement of hyphae. Ascospores are thick-walled and ellipsoid.^[5]

Parmotrema was proposed as a genus by Italian lichenologist Abramo Bartolommeo Massalongo in 1860, with Parmotrema perforatum as the type species.^[6] The genus name, composed of the Greek parmos (cup) and trema (perforation), refers to the perforate apothecia. Parmotrema was largely ignored as a genus,^[7] and its species were usually grouped in section Amphigymnia of the large genus Parmelia.^[8] Several genera previously segregated from Parmotrema have since been folded back in owing to molecular phylogenetic evidence, including Canomaculina, Concamerella, Parmelaria, and Rimelia.^[3][9]

Some species of Parmotrema can be used as a vegetable dye, such as P. crinitum. When mixed with pine sap or with water, or when first burnt to ash, lichens can provide a variety of colors such as yellow, brown, green, orange, purple, and red.^[10] Some Parmotrema species also enter commerce as part of the lichen mixture known as "black stone flower", which is sold for culinary use under several regional names. Continued large-scale harvesting of commercially traded lichens may add to extinction risk when combined with habitat loss and climate change.^[11]

• 
  Parmotrema tinctorum
• 
  Parmotrema chinense

• List of Parmotrema species