Cortinarius is a large genus of fungi belonging to the family Cortinariaceae. It includes a wide variety of mushrooms, many of which are found in forests and woodlands. These fungi are characterized by their distinctive features, such as a cobweb-like veil covering the young fruiting bodies and a rusty-brown spore print. Some species are edible, while others can be toxic. The genus is known for its ecological role, as many Cortinarius species form symbiotic relationships with trees through mycorrhizal associations. This means they help trees absorb nutrients from the soil while receiving carbohydrates in return. Due to their diversity, Cortinarius mushrooms are of interest to mycologists and foragers alike.