The Frosty Fibrecap (Inosperma maculatum) is a medium-sized fibrecap with a conical to umbonate, chestnut-brown cap. The surface is finely fibrous, and white scraps of veil sit on the cap, from a faint dusting to a distinct patch. The stem is slightly twisted, white and reddish-brown, and ranges from cylindrical to bulbous at the base.
It is widespread and common in deciduous woodland in the UK, especially with beech, and fruits from July to October. Fruiting bodies are often found on their own or in small groups.
This is a poisonous species. It contains muscarine, which can cause heavy sweating, salivation, tears and stomach upset, and severe cases can be dangerous. It must not be eaten. Other Inosperma species, such as Inosperma erubescens, are similar in build, and it is easy to mistake fibrecaps for edible woodland mushrooms. Microscopic features are often needed to separate Inosperma species with confidence.
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Distribution
Widespread and common
Habitat
In deciduous woodland, particularly with Fagus
Etymology
Inosperma comes from Greek, ino- (fibre) and sperma (seed or spore), literally "fibre spore", reflecting the genus's separation from Inocybe, whose name also refers to fibres. Maculatum is Latin for "spotted" or "stained", which fits the white veil patches speckled across the brown cap.
Associates
Fagus
Cap
The chestnut cap carries white scraps of veil, ranging from a fine dusting to a distinct patch, most often towards the centre. The fibrous surface contrasts with these pale remnants, which give the species its frosty look.
| Colour | |
|---|---|
| Surface | Rimose |
| Width | 2 - 8 cm |
Gills
Close gills that are notched or broadly attached to the stem. They are yellowish-brown, with ash-grey tones in the colouring, and the spore print is a milky coffee shade.
| Colour | |
|---|---|
| Spacing | close |
Flesh
The flesh is a mix of white, pale yellow and reddish-brown tones. It has a mushroomy smell that is hard to pin down.
| Colour | |
|---|---|
| Odour | Mushroomy, difficult to define |
Stem
The stem is slightly twisted along its length. It is finely fibrous and white and reddish-brown, and may be cylindrical or swollen into a bulb at the base.
| Colour | |
|---|---|
| Height | 4 - 10 cm |
| Width | 4 - 10 mm |
Spores
The spores are bean-shaped and smooth, measuring 9-11 x 5-6 µm.
| Colour | |
|---|---|
| Size | 9-11 x 5-6 μm |
Classification
- ↳ Phylum: Basidiomycota
- ↳ Subphylum: Agaricomycotina
- ↳ Class: Agaricomycetes
- ↳ Subclass: Agaricomycetidae
- ↳ Order: Agaricales
- ↳ Family: Inocybaceae
- ↳ Genus: Inosperma
Synonyms
- Inocybe fastigiella sensu auct. eur.
- Inocybe maculata Boud.
- Inocybe maculata f. fastigiella sensu auct. eur.
Reference Sources
T. Læssøe, J. H. Peterson (2019) Fungi of Temperate Europe Vol. 1. Princeton University Press.
G. Kibby (2023) Mushrooms and Toadstools of Britain & Europe Vol. 4. Geoffrey Kibby.
J. Stangl (2011) The Genus Inocybe in Bavaria. NuAge Print and Copy.
