Cortinarius
Cortinarius is a large genus of mushrooms commonly called webcaps. Its members often have a delicate veil between the cap and stem when young, plus rusty-brown spore prints. Some species are poisonous, some are considered edible, and many are difficult to tell apart, so appearance alone is not a safe guide.
- Group
- A genus of gilled fungi
- Common name
- Webcap or cortinar
- Spore color
- Rusty brown to brownish red
- Root partners
- Many form mycorrhizal relationships
- Safety
- Some species are highly poisonous
What is Cortinarius?
Cortinarius is a genus of gilled mushrooms in the family Cortinariaceae. It is found in many parts of the world and is considered one of the largest mushroom genera. Webcap is a familiar common name, referring to the fine, cobweb-like veil that can stretch between the cap and stem in young mushrooms. That veil is called a cortina; as the mushroom grows, it often breaks apart or disappears.
The genus includes mushrooms with varied sizes, colors, and shapes, so there is no single look that represents every Cortinarius. Their spores are typically rusty brown to brownish red, and mature gills may take on a similar shade as spores develop. Some species are vividly colored, while others are plain brown or grayish. These shared clues can suggest the genus, but they are not enough on their own to confirm a species.
- 1Root partnership
Fungal threads associate with the roots of a compatible plant.
- 2Hidden growth
The fungus grows through soil as a network of hyphae.
- 3Fruiting begins
Suitable conditions prompt a mushroom to develop above ground.
- 4Veil breaks
The young cortina tears as the cap expands and exposes the gills.
- 5Spores disperse
Mature gills release spores that may grow into new fungal threads.
How does Cortinarius grow?
Many Cortinarius species live in partnership with the roots of trees and other vascular plants. The fungus’s fine threads, called hyphae, form a network around or near roots. This relationship is known as mycorrhiza. The mushroom seen above ground is only the reproductive part of the fungus; much of its life is spent as hidden fungal growth in soil.
When conditions support reproduction, the fungus forms a fruiting body with a cap, stem, and gills. In a young webcap, the cortina can cover the gills, then tear as the cap expands. The gills produce spores, which disperse and may grow into new fungal threads under suitable conditions. A rusty spore deposit is one useful observation for mushroom study, but it cannot establish that a specimen is safe to eat.
Many species look alike, so positive identification can be difficult.
Some species are dangerously poisonous; uncertain specimens should not be eaten.
The genus occurs widely, with species associated with different plant partners.
Editorial placement to help compare; not a measurement.
Where do people encounter Cortinarius?
Webcaps turn up in forests and other habitats where their plant partners grow. Depending on the species and region, they may be associated with broadleaf trees, conifers, or other plants. Because the mushrooms grow from a largely hidden network, people usually encounter them during seasonal walks, field surveys, or mushroom-identification activities rather than seeing the fungus itself throughout the year.
Cortinarius matters to both ecology and identification. Its underground partnerships are part of the relationships between fungi and plants, while its great variety makes it a challenging group for field naturalists. Some species are noted for strong colors and have been used as natural dyes. Although some webcaps have been described as edible, that fact does not make the genus a safe target for casual collecting.
| Cortinarius | Inocybe | Galerina | |
|---|---|---|---|
| Group | A large webcap genus | A genus of gilled fungi | A genus of small mushrooms |
| Spore color | Typically rusty brown | Typically brown | Typically rusty to brown |
| Veil clue | Fine cortina in young specimens | Often lacks a cobweb-like veil | Some have a ring or ring zone |
| Safety note | Some species are highly poisonous | Some species are poisonous | Some species contain deadly toxins |
Cortinarius safety and common mix-ups
A key misconception is that a webcap can be judged safe because it resembles a familiar edible mushroom or has a pleasant appearance. Some Cortinarius species contain orellanine, a toxin associated with serious kidney injury, and some species can be lethal. Other members of the genus are considered edible, but many species are extremely difficult to distinguish. A shared common name or general resemblance does not identify a mushroom.
Never eat a wild mushroom without expert identification. A rusty-brown spore print, a veil, or a photograph may help narrow down possibilities, but none is a dependable safety test by itself. Do not taste a wild mushroom to identify it. If someone may have eaten a poisonous mushroom, contact emergency services or a poison control center promptly and keep any available sample or photographs for identification.
- 1821
The genus name Cortinarius was published by the mycologist Samuel Frederick Gray.
- 2002
A molecular study supported treating Rozites and related genera as part of Cortinarius.
- 2022
A genomic-data-based revision updated classification within the family Cortinariaceae.
How Cortinarius connects to mushroom topics
Learning about Cortinarius connects naturally to mushroom anatomy. The cap, stem, gills, veil, and spores are parts or clues that field guides describe. It also offers a useful example of mycorrhizal fungi: mushrooms are not just isolated objects above ground, but reproductive structures connected to a wider fungal network and, often, to plant roots.
Foragers and beginning identifiers can use webcaps to practice careful observation while recognizing the limits of visual matching. Comparing gill attachment, cap texture, stem features, habitat, and spore color can help specialists assess a specimen, but identification often needs more than one clue. For safety, treat an uncertain mushroom as unknown and consult a qualified local expert rather than relying on an app, a single photo, or a common name.
Common questions about Cortinarius
What is a Cortinarius mushroom?
Cortinarius is a genus of gilled fungi commonly called webcaps. Young mushrooms may have a fine, cobweb-like veil between the cap and stem, and the spores are generally rusty brown. The genus contains many species that can be difficult to tell apart.
Are Cortinarius mushrooms poisonous?
Some are highly poisonous, including species associated with orellanine, while some others are considered edible. Because many look similar and can be hard to identify, do not eat a wild Cortinarius or any uncertain mushroom. Get expert identification before considering any wild mushroom for food.
How can I identify a webcap?
A possible Cortinarius may have a cobweb-like veil when young and rusty-brown spores, but those clues do not confirm a species. Identification can require careful examination of several features and habitat, sometimes with specialist methods. Do not use an online photo match as proof that a mushroom is safe.
Where do Cortinarius mushrooms grow?
Cortinarius species occur in many regions and often grow in soil near plants whose roots they associate with. Many form mycorrhizal partnerships with trees or other vascular plants. The particular habitat depends on the species, so a local field guide or expert can help interpret a sighting.
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Written by the Pscilly editorial team and reviewed November 2026. Educational content only, not medical or legal advice. Pscilly does not sell psilocybin. Never eat a wild mushroom without expert identification.