Jeremy Bartlett's LET IT GROW blog

The Wrinkled Peach, Rhodotus palmatus, has been described as “a strong contender for the title ‘Most Beautiful British Mushroom’“, and rightly so.

In 2019 I found my first specimens of Wrinkled Peach growing on a large rotting log at Whitlingham Country Park, just a few miles bike ride from home. I visited a couple of times that year and went back in mid October 2020. This time the fruit bodies were in even better condition and were weeping a bright red liquid from their stems, almost like blood. This phenomenon is known as guttation (note 1). It was a rather damp day – the clear liquid dripping from the cap in the photograph below is rainwater.

Since my first sighting of Wrinkled Peach I have found several more specimens when out on walks in Norfolk, including beside Peddars’ Way near Holme-next-the-Sea and, just a week ago, at Bath Hills near Bungay. All were growing on old logs, probably elm.

Young Wrinkled Peach fruit bodies have a network of interconnected ridges on the cap, as in the specimen below (note 2).

A young Wrinkled Peach, Rhodotus palmatus, showing the wrinkled cap.

But later in the autumn (by November or December) this is a lot less obvious, though the pale peachy colour persists. The cap is always rubbery in texture.

Wrinkled Peach, Rhodotus palmatus. December 2021, Bath Hills, near Bungay.

The Wrinkled Peach has adnate to free, moderately spaced pink gills on the underside of the cap and the paler pink stem, which has no ring and is covered in whitish fibrils (small flecks or strands of fibrous material).

Wrinkled Peach, Rhodotus palmatus, showing gills and stem.

The Wrinkled Peach has an “indistinct” odour (which I’ve never actually noticed). Others have described its smell as “delicately fruity, likened by some to peach or apricot” and some people can detect an unbearably bad smell (note 3). The fungus apparently tastes bitter and this, combined with its rubbery texture means it is best regarded as inedible.

Rhodotus palmatus is a type of Basidiomycete fungus and a member of the family Physalacriaceae. The most well known genus in the family is Armillaria (various species of Honey Fungus) (note 4). There is just the one species of Rhodotus, R. palmatus. The fungus was originally called Agaricus palmatus, before being transferred to its current genus in 1926. Other English names include Rosy Veincap and Netted Rhodotus.

Fairly fresh dead elm (Ulmus) is the preferred host although Wrinkled Peach will grow on other hardwoods too, such as Ash (Fraxinus) and Horse Chestnut (Aesculus) in Europe  and species of Acer (maple) and Tilia (lime/basswood) and Liriodendron (Tulip Tree) elsewhere.

In the British Isles, you are most likely to find Rhodotus palmatus in southern and central England and Wales (there are 753 records on the NBN Atlas website at the time of writing). The species has a circumboreal distribution and also occurs in other parts of Europe, northern Africa, eastern North America and Asia (note 5).

Dutch Elm Disease caused the death of around 30 million elms in Britain from the mid 1970s to early 1980s and large elm trees are largely a thing of the past in much of the British Isles (note 6). The sudden abundance of dead elm wood resulted in an increase in Rhodotus palmatus but dead elm logs are now much rarer.

Rhodotus palmatus is consequently in decline and is in over half of the European fungal Red Lists. It is legally protected in Hungary and is “extinct or probably extinct” in Lithuania, Latvia and Estonia.

One of the recommended actions to conserve Rhodotus palmatus is to preserve dead wood of fallen trees, not only in forests but also in parkland and urban areas where elm or ash trees die.

But not everyone appreciates this.

When I went back to Whitlingham Country Park in late October this year the log where I’d found my fungi in 2019 and 2020 had gone, presumably “tidied up” by grounds staff (note 7).

Notes

Note 1 – This shedding of liquid is known as guttation and tends to occur when the fruit body is growing rapidly. Some fungi are very prone to this and the appearance of the liquid can be a useful identification feature. Different fungi exude different coloured fluids: while the Wrinkled Peach oozes red liquid, the Oak Bracket I found in September was oozing something resembling runny honey.

Note 2 – There are lots of much better photographs of this wrinkling, such as on the First Nature , Messiah University and Wild Food UK websites.

Note 3 – On a cold day it can be hard to detect odours from fungi and flowers.

Breathing gently on the flower or fungus can help, as for Witch Hazel flowers, but sometimes I have to pick a mushroom and bring it home in a sealed container before I can detect its scent.

Even the Stinking Earthfan (Thelephora palmata) we found in November in the Norfolk Brecks (described as “a candidate for stinkiest fungus in the forest“), didn’t smell until I breathed on it. Its distinctive garlicky, cabbagy odour only became obvious when I brought a piece home. (I actually quite like the smell, but only because I like garlicky cabbage.)

Another complication is that I am quite suggestible when it comes to smells. If someone asks me whether I can detect a particular odour, I often think I can.

Note 4 – Species of Armillaria cause white rot root disease and some species can be very destructive pathogens on a variety of woody plants. The world’s largest known organism is a  specimen of Armillaria ostoyae in Oregon in the United States, which covers more than 3.4 square miles (8.8 square kilometres) and is between 1900 and 9600 years old.

Note 5 – The Amazing Life website suggests that its fractured distribution is highly unusual for a single species unless it is being cultivated. It suggests that Rhodotus palmatus might have arrived in new areas via trade ships selling hardwood, which the fungus uses as a host.

Note 6 – Dutch Elm Disease is caused by two species of fungus: Ophiostoma novo-ulmi and Ophiostoma ulmi.

The first outbreak was caused by Ophiostoma ulmi and was first observed in north-west Europe from about 1910. The disease probably came from Asia but the “Dutch” name stuck because the fungus was first described by Dutch scientists.

A second, much more serious outbreak, was caused by Ophiostoma novo-ulmi and occurred from the 1960s onwards.

Fungal spores are spread by elm bark beetles, especially Scolytus scolytus, the Large Elm Bark Beetle. Trees are only infected once their bark is substantial enough to attract the beetles, so we still have lots of young and suckering elms. Once a tree is infected, it plugs up its own xylem vessels, cutting off water and nutrients and leading to its death.

See the Forest Research website for lots more useful information.

Note 7 – … Along with its community of other fungi, mosses and invertebrates. Hopefully the fungus still occurs in the area. James Emerson found more fruit bodies in nearby Trowse Woods, back in 2014. He also found the fungus at Catton Park, just north of Norwich, shortly before Christmas.

In mid November 2022 I visited some woods just to the east of where I’d seen my original Wrinkled Peach and found some more fruitbodies on old Elm logs, much to my joy.

Wrinkled Peach, Rhodotus palmatus.