About Cladonia gracilis (L.) Willd.
Cladonia gracilis, commonly called the smooth cup lichen, is a species of fruticose cup lichen belonging to the family Cladoniaceae. It was first formally described as a new species by Carl Linnaeus in his 1753 publication Species Plantarum. In 1787, German botanist Carl Ludwig Willdenow moved the species to the genus Cladonia. In North America, it is also known by the common name "smooth Cladonia".
The Cladonia gracilis group is a monophyletic group of species that all share similar morphological characteristics with C. gracilis. Within this group, defining clear species boundaries is challenging. This difficulty arises from the close morphological similarity between different taxa in the group, and because many of the traits used to classify these species are affected by environmental factors including light exposure, temperature, and humidity.
