Inocybe geophylla - White Fibrecap

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

Inocybe geophylla is a very common species and is sometimes mistaken for small field mushrooms (Agaricus campestris) with disastrous results: it is very poisonous and its consumption can be fatal.

Although known to be mycorrhizal with deciduous broadleaf trees and with conifers, this little white mushroom is also a very common find on damp disturbed roadside mud that is rich in leaf litter.

Identification guide

	Cap There are two common varieties of this species: the White Fibrecap, Inocybe geophylla, and a variety commonly referred to as the Lilac Fibrecap, Inocybe geophylla var. lilacina (left). The smooth, silky cap has a diameter of 1.5 to 3.5cm; initially conical, it flattens as it matures, usually retaining a pointed umbo and streaky radial fibres that in dry weather tend to tear into strips towards the edge of the cap. Both the white and lilac varieties fade to ochre-brown from the centre as the fruitbody ages.
Gills	The crowded gills, which are notched or adnexed, start off creamy-grey and later turn clay-brown as the spores mature.
Stem	3 to 6mm in diameter and up to 6cm tall, the stipe is smooth and silky, sometimes slightly fibrillose towards the base, and the same colour as the cap. The stipe also gradually turns clay-brown with age.
Spore print	Dull brown.
Odour/taste	Slightly earthy or mealy smell. Reported to have a mild taste (but please be aware that this is a deadly poisonous fungus and so tasting any part of it is not advisable).
Habitat	Beside paths and on roadside verges beneath deciduous trees and in mixed woodland; less frequently under conifers.
Season	Summer and autumn.
Occurrence	Very common.
Similar species	The White Fibrecap, Inocybe geophylla, could be confused with Agaricus campestris, which is usually much larger, has a stem ring and does not have a silky cap.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2011

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.