Mycena acicula (Schaeff.) P. Kumm. - Orange Bonnet

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Mycenaceae

Mycena acicula, Orange Bonnet, southern England

Despite the striking colour, these bonnet mushrooms are easy to overlook because they are so small. Rarely are the caps much more than 1cm across, and they tend to become obscured in the moss and leaf litter of the woodland floor.

Look out for these pretty little mushrooms in damp deciduous broadleaf woodlands. Most often you can expect to find them in areas of deep shade, where they grow attached to small dead twigs buried beneath the top layer of leaf litter.

Mycena acicula, Orange Bonnet, southern Portugal

Most Mycena species have dull caps, and it may be that this and a few other small and brightly-coloured bonnet fungi are only distantly related to the other larger and duller bonnets currently - Classified in the same genus.


In Britain and Ireland the Orange Bonnet is widespread and fairly common. This striking little bonnet mushroom occurs throughout mainland Europe and many other parts of the world including North America.

Taxonomic history

German mycologist Jacob Christian Schaeffer described the Orange Bonnet in 1762, giving it the binomial scientific name Agaricus acicula. It was another German, Paul Kummer, who in 1871 transferred this species to its present genus, thus establishing its currently-accepted scientific name Mycena acicula.

Synonyms of Mycena acicula include Agaricus acicula Schaeff.Agaricus miniatus Batsch, Hemimycena acicula (Schaeff.) Singer and Trogia acicula (Schaeff.) Corner.


The specific epithet acicula means 'with bristles, pins or needles'.

Identification guide

Cap of Mycena acicula


0.5 to 1.8cm across; conical, becoming bell shaped; smooth with marginal striations; reddish when very young but soon becoming mid to dark orange and often a lighter shade of orange or yellow towards the rim. The cap surface is finely pruinose at first but soon becomes smooth. Occasionally you may come across slightly papillate (narrowly umbonate) specimens.


Adnexed to almost free; white or pale yellowish-orange with paler gill edges.


3 to 5cm long and 1 to 2mm in dia.; yellow; smooth or slightly powdery, particularly towards the apex; no ring.



Fusiform, smooth, 8.5-10 x 2.5-3.5 µm; inamyloid.

Spore print



Not distinctive.

Habitat & Ecological role

Among mosses and leaf litter on deciduous woodland floors.


July to November in Britain and Ireland.

Similar species

A similar woodland mushroom Mycena adonis, known as the Scarlet Bonnet, is also very small. An occasional find in both deciduous hardwood forests and in conifer plantations, the Scarlet Bonnet differs in having a reddish-orange or bright pink cap, and its stem is usually white (but red in var. adonis). Both species tend to occur as singletons or in small scattered groups.

Culinary notes

These little fungi are far too small and insubstantial to be of culinary interest. It is unclear whether they are toxic or not.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Giovanni Robich, (2003). Mycena d'Europa; Associazione Micologica Bresadola ; Vicenza : Fondazione Centro Studi Micologici.

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.


This page includes pictures kindly contributed by Simon Harding.

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