Panaeolina foenisecii (Pers.) Maire - Brown Mottlegill

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Insertae sedis (Not yet assigned)

Panaeolina foenisecii - Brown Mottlegill

Also commonly referred to as the Mower’s Mushroom and the Haymaker, Panaeolina foenisecii springs up on any lawn that is regularly mown but not intensively dosed with lots of artificial fertilisers or selective herbicides. It is probably the most common of the ‘common or garden’ lawn mushrooms, and unfortunately it is inedible and can cause sickness if eaten. (Toddlers are particularly vulnerable!)

Panaeolina foenisecii - Brown Mottlegill showing the caps drying out and turning buff from the centre

The hygrophanous nature of the cap means that colour is not a significant identifying feature; some caps may be dark brown while others, in drier parts of the same lawn, may be a pale creamy-beige that appears white in bright sunlight.

Distribution

Brown Mottlegill fungi occur in most parts of the world. They are very common and widespread throughout Britain and Ireland as well as on mainland Europe and in North America.

Panaeolina foenisecii, mature specimens

Taxonomic history

This species was described in 1800 by Christiaan Hendrick Persoon, who named it Agaricus panaeolinia (at a time when most gilled fungi were initially placed in the Agaricus genus, since largely distributed across many newer genera). French botanist and mycologist René Charles Joseph Ernest Maire (1878-1949) transferred the Brown Mottlegill to its present genus in 1933.

Panaeolina foenisecii is the type species of the Panaeolina genus, which contains very few species (and only this one in Britain).

Down the ages this ubiquitous little brown mushroom has acquired many synonyms including Agaricus foenisecii Pers., Prunulus foenisecii (Pers.) Gray, Psilocybe foenisecii Pers.) Quél., Psathyra foenisecii (Pers.) G. Bertrand, Panaeolus foenisecii (Pers.) Kühner, and Psathyrella foenisecii (Pers.) A.H. Sm.

There is no concensus about the correct taxonomic position of fungi in the genera Panaeolus and Panaeolina, which some authorities include in the family Strophariaceae and others in the Bolbitiaceae. (I have placed our pictures of this species in with those of other members of the family Bolbitiaceae.)

Panaeolina foenisecii - close-up picture of mottled gills

Etymology

Panaeolina, the genus name of this little brown mushroom, suggests that this species has similarities with those in the genus Panaeolus. Panaeolus means variegated - and indeed the caps of many Panaeolus species are zoned, but the generic name is not a reference to the cap colouring but to the mottled or variegated colouring of the gills. The mottling on the gills of Panaeolina foenisecii is illustrated on the left; this effect is due to patches of spores of different parts of the gill surface reaching maturity at different times. One other obvious difference between fungi in these two genera can be seen provided you have access to a high-powered microscope: you will see that the spores of Panaeolus fungi are smooth while those of Panaeolinus are minutely roughened.

The specific epithet foenisecii simply refers to haymaking.

Toxicity

There is evidence that children can become ill after eating theses little brown mushrooms, and so on a precautionary basis at least they should be treated as toxic toadstools and not gathered for eating. (Depending on where in the world they are growing, there is research showing that there can be small amounts of psilocybin in some these fungi, but almost certainly at much too low a concentration for them to be hallucinogenic.)

Identification guide

Cap of Panaeolina foenisecii, Brown Mottlegill

Cap

1 to 2cm across, caps are initially bell-shaped or conical, expanding to become broadly convex; hygrophanous, medium to dark brown when moist, drying from the centre outwards to a creamy-beige.

Gills of Panaeolina foenisecii

Gills

Gills of Panaeolina foenisecii are adnate; pale brown at first becoming mottled dark brown.

Stem

Stems of the Brown Mottlegill are 4 to 7cm long and 3 to 5mm diameter; cream flushed towards base with mid brown; cylindrical; finely fibrillose; no stem ring.

Spores of Panaeolina foenisecii

Spores

Lemon shaped with a roughened surface and a germ pore (see picture, left). Dimension range 11-18 x 6-9µm.

Show larger image

Spore print

Dark brown.

Odour/taste

Odour is slightly unpleasant but not diagnostically distinctive.

Habitat & Ecological role

Saprobic, on lawns, roadside verges and other grassy places.

Season

April to December in Britain and Ireland.

Similar species

Stropharia semiglobata, the Dung Roundhead, has a transient ring and leaves a brown spore print.

Panaeolus fimicola, the Turf Mottlegill, has a dark-brown cap when wet and dries out to become mid brown.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

British Mycological Society. English Names for Fungi

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.

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