Agaricus xanthodermus, commonly known as the yellow-staining agaricus, yellow-staining mushroom or yellow-stainer, is a species of fungus in the genus Agaricus. It displays a strong yellow colouration at the base of the stem when cut. It has a phenolic smell. It is poisonous for most people, causing gastric upset, but can be eaten by some without apparent negative effect.
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Distribution
Common
Habitat
In open grass or soil by woodland margins, hedgerows, gardens, parks etc. Rarely in dense woodland
Cap
Staining bright yellow
| Colour | |
|---|---|
| Shape | Flattened, Expanded |
| Surface | Smooth, Squamose, Cracking |
| Width | 6 - 15 cm |
Gills
| Colour | |
|---|---|
| Attachment | Free |
| Spacing | crowded |
Flesh
Yellow at base of stem
| Colour | |
|---|---|
| Odour | Unpleasant, phelonic, ink |
| Taste | Mild |
Stem
Large, thin ring with cogwheel scales on the margin of underside
| Colour | |
|---|---|
| Height | 6 - 12.5 cm |
| Width | 10 - 18 mm |
| Texture | Smooth |
| Shape | Bulbous, Clavate |
| Veil | double-rings |
| Veil position | superior |
| Bruising |
Macrochemicals
KOH on cap is positive
Spores
| Colour | |
|---|---|
| Shape | Broadly ellipsoid |
| Ornamentation | Smooth |
| Size | 4.5-6.5 x 3.5-5.5 μm |
Microscopic Features
| Cheilocystidia | Club-shaped (Clavate) |
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Classification
- ↳ Phylum: Basidiomycota
- ↳ Subphylum: Agaricomycotina
- ↳ Class: Agaricomycetes
- ↳ Subclass: Agaricomycetidae
- ↳ Order: Agaricales
- ↳ Family: Agaricaceae
- ↳ Genus: Agaricus
Synonyms
- Agaricus xanthodermus subsp. lepiotoides Maire
- Agaricus xanthodermus var. griseus (A. Pearson) Bon & Cappelli
- Agaricus xanthodermus var. lepiotoides Maire
- Agaricus xanthodermus var. xanthodermus Genev.
- Psalliota flavescens Richon & Roze
- Psalliota xanthoderma
- Psalliota xanthoderma (Genev.) Richon & Roze
- Psalliota xanthoderma var. grisea A. Pearson
- Psalliota xanthoderma var. grisea Pearson
- Psalliota xanthoderma var. lepiotioides (Maire) Rea
- Psalliota xanthoderma var. lepiotoides (Maire) Rea
Reference Sources
S. Buczacki, C. Shields, D. Ovenden (2012) Collins Fungi Guide. HarperCollins.
T. Læssøe, J. H. Peterson (2019) Fungi of Temperate Europe Vol. 1. Princeton University Press.
G. Kibby (2021) Mushrooms and Toadstools of Britain & Europe Vol. 3. Geoffrey Kibby.
G. Kibby (2020) The Genus Agaricus in Britain. Geoffrey Kibby.
