About Nephroma helveticum Ach.
Nephroma helveticum, commonly called the fringed kidney lichen, is a species of cyanolichen belonging to the family Peltigeraceae. It was first formally described by Erik Acharius in 1810, and it is part of a complex taxonomic group that also includes N. tropicum. Modern molecular research has found that material that was previously classified as N. helveticum actually consists of two separate distinct species. This species grows in moist, shady environments, most commonly in old-growth forests. In North America, it occurs at low elevations in riparian areas that experience coastal influence. In Europe, where it is extremely rare, it grows in montane-oceanic regions and prefers basic rock substrates. Across Finland, Norway and Sweden, the three Nordic countries where it is found, it is known from approximately 20 localities and is classified as critically endangered. As a species complex, Nephroma helveticum has a cosmopolitan distribution, with distinct habitat preferences across its range. In North America, it typically grows in moist, shady environments at low elevations, especially in old-growth riparian forests and regions with strong coastal influence. In Europe, where it is extremely rare, the species has a montane-oceanic distribution and is limited to undisturbed, humid old-growth forests. In Scandinavia, it shows a strong preference for basic rock substrates, though it may occasionally grow as an epiphyte on tree bark.
