Pammelia

Pammelia is a genus of foliose lichenized fungi belonging to the family Parmeliaceae. Lichens of the Pammelia genus are characterized by their relatively large, leafy (foliose) thalli, typically grey to brown in color, and often exhibiting lobes with rounded or irregular margins. They are commonly found growing on rocks, trees, and soil in various habitats worldwide, ranging from temperate to arctic regions.

Historically, Pammelia was a broadly defined genus encompassing a diverse array of species. However, with advancements in molecular phylogenetics, the genus has been significantly revised, and many former Pammelia species have been reclassified into other genera within the Parmeliaceae family, such as Parmelia, Hypotrachyna, Melanohalea, and others. The modern circumscription of Pammelia is thus more restricted than in the past.

Key features often used to identify Pammelia species (in their revised sense) include:

• Thallus Morphology: Foliose, with lobes that are often loosely attached to the substrate.
• Upper Surface: Typically grey, brown, or olive-brown, often with a network of ridges or cracks.
• Lower Surface: Darker, often black, and usually with rhizines (root-like structures) for attachment.
• Reproductive Structures: Pammelia can reproduce both sexually via apothecia (cup-shaped fruiting bodies) and asexually via soredia (powdery propagules) or isidia (small, cylindrical outgrowths).

Due to the ongoing taxonomic revisions, identification of Pammelia species can be challenging and often requires microscopic examination of reproductive structures and chemical analysis of lichen substances. Understanding the current taxonomic status is essential for accurate species identification and ecological studies involving these lichens.