Cortinarius, also known as Webcaps, is one of the largest genera of mushrooms, with over 2,000 described species found in forests around the world. These mushrooms live in symbiosis with trees, forming ectomycorrhizal relationships that help roots absorb nutrients in exchange for sugars (Liimatainen et al., 2022). A key feature of this group is the cortina — a thin, cobweb-like veil that covers the gills in young mushrooms and often leaves faint fibers on the stem as it breaks. Webcaps also leave a distinctive rusty brown to reddish brown spore print, which is useful for identification (Healy et al., 2020).

Webcaps come in a wide range of colors, from deep violet and rusty orange to muted browns and yellows. Some species are strikingly beautiful, but many are difficult to identify without microscopy or DNA sequencing. A few species in this genus contain orellanine, a dangerous toxin that can cause delayed-onset kidney failure (Beug, 2024). Because of the potential for confusion with toxic lookalikes, Cortinarius mushrooms are not recommended for foraging without expert knowledge, though beautiful for appreciating the wonderful colors in the field.

References

Beug, M. (2024, April 23). Mushroom Poisoning Syndromes – North American Mycological Association. North American Mycological Association. https://namyco.org/interests/toxicology/mushroom-poisoning-syndromes/

Healy, R. A., Ammirati, J. F., & Liimatainen, K. (2020). Cortinarius tiffanyae sp. nov. Index Fungorum, No. 456, 1. https://www.indexfungorum.org/Publications/Index%20Fungorum%20no.456.pdf

Liimatainen, K., Kim, J. T., Pokorny, L., Kirk, P. M., & Niskanen, T. (2022). Taming the beast: A revised classification of Cortinariaceae based on genomic data. Fungal Diversity, 112(1), 89–170. https://doi.org/10.1007/s13225-022-00499-9