Weird and Wonderful Wild Mushrooms: A Teratological Mystery from 1744: Agaricus ramosus/Boletus ramoso/Boletus rangiferinus/Polyporus squamosus

Ehret Agaricus ramosus or abnormal growth of Polyporus squamosus

Georg Dionysius Ehret's 1744 illustration
of "Agaricus ramosus"

I was leisurely poking around the Wellcome Library's astonishing collection of hi-res historical images when I was stopped in my tracks by this fabulous, otherworldly image of a fungus. What the heck is it supposed to be?

My first thought was that it was either a poor rendering, or something invented. But the man who made this hand-painted engraving was no slouch. In fact, he was one of the most celebrated botanical illustrators of his time: Georg Dionysius Ehret. Born in Germany in 1708, Ehret began his career as a gardener at a local castle. But he also studied and drew plants and insects with enough detail that before he was thirty he was already collaborating in Holland with Carl Linnaeus in the production of the important botanical work, Hortus Cliffortianus. Eventually he moved to London where he specialized in illustrating the numerous exotic plants that were regularly being brought to England from the colonies. He was lauded not just for his style, but also for his anatomical accuracy in rendering these plants.

Ehret Selenicereus gradiflorus 1750 from Plantae selectae

Ehret's 1750 illustration of Selenicereus
grandiflorus from Plantae selectae

Though he rarely depicted fungi, it's obvious that Ehret knew what he is doing. Which means we have to assume that the illustration of the antlered fungus must be a fairly faithful rendering of what was found growing in Mr. Winckles’ cellar.

Ehret's 1760 watercolour of "Helvella mitra"—a rare, for him, rendering of a fungus.

But What the Heck Is It?

Ehret's description of Agaricus ramous Ployporus squamosus

Close-up of Ehret's description of Agaricus ramosus

Though called "Agaricus ramosus," the fungus depicted is clearly not an Agaricus of any kind, certainly not as we now know the genus; Agaricus species all have gills, and Ehret clearly states—and shows—that this “plant” has pores. Of course, 1744 was early days in terms of fungal taxonomy and, at the time, the name Agaricus was widely applied to many fungi, including polypores.

With no other clues, I Googled "Agaricus ramosus" to see what would happen. The first page of hits turned up nothing other than reproductions of the same illustration—no help at all. Mycobank was also no help, nor, surprisingly, was Index Fungorum, the international index of formal fungi names. I plowed on and eventually found reference to Ehret's fungus in a 1745 issue o f The Royal Society’s Philosophical Transactions, a copy of which, despite being 270 years old, was easy to find (I can't tell you how much I love the World Wide Web!):

"An Account of a New Species of Fungus by John Martyn [professor of botany, Cambridge] communicated in a Letter to the President:

“In the latter Part of the Summer of the Year 1744, Mr Ehret the Painter brought me a Fungus of a very extraordinary Shape and Size, which had been found growing on a Piece of the Trunk of an Elm, in a damp Cellar in the Hay-Market.

“The whole Plant was about two Feet in Height; and, at first Sight, seemed not very unlike the Horns of some Deer, being variously branched, and covered with a thick Down. It was of a spongeous Substance, and of a dusky-red Colour inclining to Black. The Tips of the smaller Branches were of a Cream-Colour. The larger Branches or rather the Tops of the whole Plant, were expanded in Form of a Funnel, smooth on the concave, and full of Pores on the convex Side. The inner and lower Part of the Funnel was of the same Colour with the Stalk; the rest of it was of a cream-Colour.

“I have not been able to find, that this Plant has been mentioned by any Author: and I am persuaded, that it is a new Species; and, perhaps, the remarkable branching of the Stalks may induce some to think it a new Genus..."

Martyn, however, goes on to decide that it is not a new genus, and, because its cap is not lamellated, he makes it a Boletus, settling on the name Boletus ramoso—a name that goes absolutely nowhere on the internet.

But then I discover that Ehret’s image had been listed in a library catalogue as Boletus rangiferinus, a name James Bolton came up with in 1888 after being shown what he described as a

"curious and extraordinary fungus growing on a Log of Wood, in the cellar of a Publick House in Leeds, in the beginning of October...I had an opportunity of drawing it when fresh and newly gathered, but it is in the possession of a Man, of such a temper (who is no Naturalist) that no offers I could make him would prevail him to part with it!"

I typed Botetus rangiferinus into Google...

...and Suddenly Everything Falls into Place

It turns out that this bizarre antlered fungus that grows in dark, dank cellars, descriptively named Agaricus ramous and Boletus ramosa and Boletus rangiferinus (ramose=branched and rangifer=reindeer), is none other than—drum roll, please—an abnormal, or teratological form of the extremely common, cosmopolitan wood decayer, Polyporus squamosus, aka Dryad's Saddle (a name that goes back hundreds of years) or Pheasant's Back (a 20th century name). Whatever you prefer to call it, P. squamosus apparently does very peculiar things in the dark.

Edible Polyporus squamosus, Pheasant back, Dryad's saddle

Perfectly normal Polyporus squamosus growing on a standing dead elm

There are other descriptions of this "cellar fungus" "monstrosity" to be found on the internet. According to an article in the The Midland Naturalist (1888), one was found in a wine cellar with a

"dark coloured base about six inches wide, and from this arose a number of clavaria-like processes, some of which were branched. These clavaria-like branches were from three to six inches long, and were of a pale fawn colour."

Another, smaller example, was found growing in the rafters of a house when a floor was removed for repairs.

And then I found another illustration of the antler deformity, this one by James Sowerby in English Fungi or Mushrooms (1797). That sure looks like an antler to me.

mutant mushroom Polyporus squamosus James Sowerby, English Fungi or Mushrooms (1797)

A clearly depicted Polyporus squamosus "antler" by
James Sowerby in English Fungi or Mushrooms (1797)

One can hardly blame those who saw these "antler" growths to think they'd stumbled across an unnamed species. I would probably have thought the same thing, particularly since the first time I found baby P. squamosus—having only seen large mature ones before—I initially didn't have a clue what they were...and they weren't even sporting black antlers. But I'd like to see the "clavaria-like" form, so I have a mind to take a chainsaw out back and cut a piece off a productive dead elm to put in my root cellar to see if I can grow my own teratological P. squamosus formation.