HUMUNGOUS FUNGUS

I thought it might be honey fungus at first (Armillaria mellea), but it grew far too large. Much searching through my mycology books narrowed it down to a few possibilities but did not resolve it, so I carefully collected the specimen, as photographed above. This is a bit like picking a fruit rather than digging up a plant and does not kill the mycelium from which the fungi grow, so I did not feel guilty. I took a spore print (see left) by resting the fungus on a sheet of white paper overnight, looked at the spores under the microscope and asked our local naturalists for help. It turned out to be Gymnopilus junonius (Fr.) P.D.Orton (1960), known in the vernacular as the spectacular rustgill or laughing gym, the latter name perhaps referring to some of the genus that contain mind-altering chemicals. The cap can be as much as 30cm in diameter. The spores are tiny, 7.5 – 10 x 5.6 μm, oval/almond-shaped and pale lemon, aging to brown.

A famous Swedish botanist and mycologist, Elias Magnus Fries (1794 – 1878), described this fungus in 1821 and referred to it then as Agaricus junonius. It is not edible and contains a neurotoxic/cytotoxic poison; it is probably hallucinogenic. I certainly did not eat any of it! The specific epithet junonius presumably reminded Fries of Juno the Queen of the Gods – perhaps he thought this was the queen of mushrooms. It is certainly spectacular, as reflected in its earlier specific name spectabilis. Gymnopilus is derived from the ancient Greek γυμν (as in γυμνάσιον gymnasium – the ancient Greeks used to exercise naked) and πῖλος, a felt cap or hat, so “naked cap”. 

Although not an uncommon species, very large fungi in this classic  “mushroom” shape are unusual as the great majority are much smaller. This one took several weeks to develop from a small button and did not appear almost overnight as many autumn fungi do. They can grow in large clusters, although that was not the case in this instance. The record has been sent to the Biological Records Centre which is something we recommend anyone to do when they make any unusual find. It helps us with monitoring biodiversity and mapping species’ ranges. G. junonius is found in several parts of Europe, Asia and North America. 

Betts Ecology are keen to record unusual fungi on our sites, so please send us details with clear photographs, including the habitat and exact location, if you find any. 

Fungal mycelia in the soil and elsewhere are exceptionally important as a carbon sink and consequently in fighting climate change. There can be over 100km of fungal mycelia in half a cup (a handful, say) of soil. We must do all we can to preserve natural and semi-natural ecosystems without disrupting the growth and ecological wellbeing of fungi which deliver such an important ecosystem service. That means avoiding fungicides, proscribing ecologically unsound land-use and over-development, and minimising intensive agriculture. 

© Betts Ecology