Gassy Webcap
cortinarius traganus
The Gassy Webcap (Cortinarius traganus) is a distinctive and intriguing mushroom species belonging to the large and diverse family Cortinariaceae. Known for its striking appearance and highly unusual scent, this fungus is a key player in coniferous forest ecosystems across the Northern Hemisphere. It is easily recognized by its initial pale lilac to silvery-violet color, which beautifully carpets forest floors, though it quickly shifts to a dull yellowish-brown as it matures. What truly sets this species apart, however, is its notorious odor. The mushroom emits a powerful, unpleasant chemical aroma often described as resembling acetylene gas, goat sweat, or rotting pears. This pungent scent acts as a natural deterrent against many woodland herbivores. Beneath its lilac skin, the inner flesh of the Gassy Webcap is a surprising saffron-yellow or rusty-orange, creating a vivid contrast for foragers who cut it open. While visually captivating, this mushroom is inedible and mildly toxic, causing gastrointestinal distress if consumed. It forms vital ectomycorrhizal partnerships with evergreen trees, assisting them in nutrient absorption.
Habitat: Found in coniferous and mixed forests, particularly under spruce and pine trees, on acidic soils.
Appearance
This mushroom features a convex cap measuring 4 to 12 cm in diameter, which gradually flattens and develops a yellowish-brown center while maintaining pale lilac-violet edges. When young, a pale violet, cobweb-like partial veil (the cortina) covers the gills, later leaving rusty-brown spore remnants on the thick, bulbous stem. The gills underneath start as a dirty saffron-yellow before turning dark rusty-brown as the spores mature. Its robust stipe is 5 to 10 cm tall, matching the cap's violet hue externally, but cutting it open reveals a dense, distinctly saffron-yellow to ochre-brown interior.
Category
FungiRarity
Common
Danger
1/5 · Very low
Snaps
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Interesting facts
Despite its attractive lilac-purple exterior, its inner flesh is a shocking saffron-yellow or rusty-brown color.
It is considered mildly toxic or inedible, with a highly bitter taste that matches its offensive scent.
The Gassy Webcap gets its common name from its pungent, chemically sweet odor, which is often compared to coal gas, acetylene, or rotten pears.
Special abilities
Chemical Scent Defense
Emits a powerful, disagreeable odor resembling acetylene gas, which deters many potential herbivores from consuming it.
Cortina Web Protection
Features a delicate, cobweb-like partial veil that protects the developing gills and immature spores from pests and drying out.
Mycorrhizal Nutrient Exchange
Establishes a highly efficient subterranean network with conifer roots, exchanging soil nutrients and water for tree-produced carbohydrates.
Measurements & details
- Length
- 5-12 cm
- Weight
- 0.05-0.2 kg
Diet & Feeding
Absorbs carbohydrates and organic sugars directly from its symbiotic host trees in exchange for soil minerals and water.
Primary Foods
- Carbohydrates from host tree
- Water
- Soil nitrogen
- Phosphorus
Foraging Method
- Symbiosis
Ecological connections

Norway Spruce
Picea abies
Establishes a mutualistic ectomycorrhizal partnership, exchanging water and soil nutrients for tree sugars.

Scots Pine
Pinus sylvestris
Serves as an alternative host tree for mycorrhizal associations in northern pine woodlands.
Fungus Gnat
Mycetophila fungorum
The larvae of this insect burrow into and feed on the fungal flesh of the fruiting body.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
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Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify Gassy Webcap?
The easiest way to identify Gassy Webcap is to use the Snappit nature identifier app.
How long is Gassy Webcap?
5-12 cm
How much does Gassy Webcap weigh?
0.05-0.2 kg
What does Gassy Webcap eat?
Absorbs carbohydrates and organic sugars directly from its symbiotic host trees in exchange for soil minerals and water.
Where is Gassy Webcap usually found?
Found in coniferous and mixed forests, particularly under spruce and pine trees, on acidic soils.
How does Gassy Webcap hunt?
Symbiosis
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