The Sulphur Knight (Tricholoma sulphureum) is a bright yellow mushroom with one of the most memorable smells in British woodland: coal gas, or an old gasworks. It is yellow all through, from the dry, finely felty cap, often tinged reddish-brown at the centre, to the broad, notched gills, the fibrous stem and even the flesh.
It grows mostly with oak and beech on richer soils, and sometimes with pines, from August into November.
It is poisonous, causing stomach upsets, though the smell is warning enough. The Yellow Knight (Tricholoma equestre) has a greenish-yellow cap with a brownish centre and no gas smell. It is unsafe too: it has been linked to serious muscle damage in people who ate it repeatedly. Yellow waxcaps are waxy and grow in grassland.
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Distribution
Widespread and common
Habitat
Mostly on rich soils with deciduous trees but sometimes conifers
Etymology
Tricholoma is from the Greek thrix, 'hair', and loma, 'fringe', though few species have a hairy cap edge. sulphureum is Latin for 'sulphur-coloured'.
Associates
Fagus, Pinus, Quercus
Cap
Convex, sometimes with a low umbo, 2.5-10 cm across, with a dry, matt surface that is smooth to minutely tomentose (finely downy). The colour is bright yellow, often with reddish-brown or olive tints towards the centre.
| Colour | |
|---|---|
| Shape | Convex, Umbonate |
| Surface | Smooth, Tomentose |
| Width | 2.5 - 10 cm |
Gills
Sulphur-yellow and broad, notched where they meet the stem.
| Colour | |
|---|---|
| Attachment | Emarginate |
| Spacing | crowded |
Flesh
Yellow throughout and firm, with the gas smell strongest when cut.
| Colour | |
|---|---|
| Odour | Strong of coal gas |
| Taste | Bitter farinaceous |
Stem
Yellow with fine reddish-brown fibres; no ring.
| Colour | |
|---|---|
| Height | 2.5 - 4 cm |
| Width | 6 - 10 mm |
| Texture | Fibrillose |
| Shape | Cylindric |
Spores
| Colour | |
|---|---|
| Shape | Ellipsoid |
| Ornamentation | Smooth |
| Size | 8.5-11 x 5-6.5 μm |
Classification
- ↳ Phylum: Basidiomycota
- ↳ Subphylum: Agaricomycotina
- ↳ Class: Agaricomycetes
- ↳ Subclass: Agaricomycetidae
- ↳ Order: Agaricales
- ↳ Family: Tricholomataceae
- ↳ Genus: Tricholoma
Synonyms
- Agaricus bufonius Pers.
- Tricholoma bufonium (Pers. ex Fr.) Gillet
- Tricholoma bufonium (Pers.) Gillet
- Tricholoma sulphureum (Bull. ex Fr.) P. Kumm.
- Tricholoma sulphureum var. bufonium (Pers. ex Fr.) Quel.
- Tricholoma sulphureum var. bufonium (Pers.) Quél.
Reference Sources
T. Læssøe, J. H. Peterson (2019) Fungi of Temperate Europe Vol. 1. Princeton University Press.
R. Phillips (2006) Mushrooms. Macmillan.
G. Kibby (2020) Mushrooms and Toadstools of Britain & Europe Vol. 2. Geoffrey Kibby.
G. Kibby (2017) The Genus Tricholoma in Britain. Geoffrey Kibby.
