Species details
Yellow stainer
Agaricus xanthodermus
Poisonous
Photo: Chilepine · Public Domain · Photo source · License
Description
A white agaric that stains bright yellow when rubbed, especially at the base, and often smells of phenol or ink.
Identification features
The gills begin pink and become chocolate brown. Yellow staining at the base is rapid and strong.
Identification checklist
The white to greyish cap yellows when bruised, with the cut stem base turning especially bright chrome-yellow. It smells phenolic—like ink, iodine, or disinfectant—often more strongly when heated; the gills become brown with age.
Detailed features
- Cap
- 5–15 cm, initially almost globose, later broadly convex, white to greyish; rapidly chrome-yellow when rubbed.
- Hymenophore
- Gills are free, initially off-white, then pink and finally grey- to dark brown.
- Stem
- White and smooth, with a large hanging ring and bulbous base; flesh at the stem base rapidly turns bright yellow when cut.
- Flesh
- White; the characteristic intense yellow staining is strongest at the stem base.
- Smell
- Of ink, phenol or iodine, especially strong after cutting the stem base and during cooking.
- Spore print
- Very dark brown.
Size
- Cap diameter
- 5–15 cm
- Stem diameter
- 1–2 cm
Habitat
In grassland, gardens, parks, pathsides, and nutrient-rich soil.
Fruiting period
May, June, July, August, September, October, November
Ecology
- Trophic mode
- Saprotrophic
- Substrate
- Soil, Disturbed soil
Distribution
- Notes
- Widespread in Europe, especially in parks, gardens, hedgerows and disturbed ground.
How to separate similar species
Meadow and horse mushrooms may also yellow slightly but lack the strong yellow reaction at the stem base and the phenolic smell. Assess colour change and odour together, not as isolated features.
Similar species
Interesting facts
Did you know? The name xanthodermus means 'yellow-skinned'; rapid strong yellow staining and a phenolic smell are key warning signs.