Tall trees and Mushrooms

After there has been a bushfire in the forests around here, and in fact in many parts of Australia, there are a number of fungi that are triggered to send up fruiting bodies. One of these is Laccocephalum mylittae  (formerly Polyporus mylittae), known in early colonial times as Blackfellow’s bread. This is because it was eaten by the Aboriginal people and it has a sclerotium with a texture rather like grains of cereal pressed together. When sliced it is dense like pumpernickel. This fungus may well have been consumed as a food for tens of millenia. It is widespread across the country.

The fungus spends most of its existance feeding on fallen or buried logs. From this woody matter it transports material to a large underground sclerotium which slowly grows in size. It is reported to grow to as large as 600 mm diameter, but the ones I have seen have been about the size of a football. The sclerotium is heavy, with an estimated relative density of 1.1. This growth may go on for 30 years or more, until there is a fire to trigger off the cycle. The sclerotium rapidly sends forth a fruiting body which is apparent at the surface of the ground within a couple of days of the fire. These are commonly seen along side fallen logs. In my part of the world it occurs in Karri forest.  The mushroom is fairly non-descript at first, eventually becoming more defined as it consumes the sclerotium over a period of about a month.

Here is a young mushroom with the sclerotium attached. The mushroom is white, whereas the sclerotium has a dark brown skin covering it.

One can easily imagine that the Aboriginal people would have swept through areas they had burned a couple of days earlier to harvest the scelorotiums, which can be quite numerous. Being dense, they provide a significant food source and they do not appear to decay rapidly. They can be crumbled up and dried out into something resembling a cereal grain. Whether the Aboriginal people did this is probably unknown. The picture below shows the scerotium cut open to reveal the inner texture.

It is entirely possible that this fungus could be cultivated like any other wood rotter. I have a specimen that I will attempt to clone if I have the time and inclination. It might make an interesting addition to our native food cuisine. I would describe the taste as bland, but a friend found it to be quite pleasant. It would lend itself to some creative cooking. Apparently, it has significant nutritional value.

The mature specimen is shown below. It can be seen that the mushroom has grown, while the sclerotium has become depleted.

The spores of this species are shown in the image below.  These measurements were done using the software called Piximetre.   I am still mastering this software, the instructions of which are written in French, but I think this captures the main features.   The average spore size is 9.4*4.3 microns. More detailed statistics are shown.  These spores were stained with Melzer’s so judging by the image they do not appear to be amyloid.  The measurement shown in blue is from my microscope software which was calibrated with an etched slide.  The image is taken at 40X without oil.

The structure of the pore surface is shown in this image. The spaces on the scale are 1mm.

The pore depth is slightly greater than 2 mm.

March 2025

The gelatinous mass that makes up the bulk of the sclerotium is an interesting material. It occurs as distinct pieces that have white thread-like material between them. The whole mass can be broken up into individual grains manually with some effort. I had thought that this material might contain starch, but when tested with Melzer’s reagent (which contains iodine) it did not produce a blue colour, indicating that starch was not present. Disintegrating some in a blender with some water produced a slightly cloudy liquid. When tested with alkaline copper sulfate (Biuret test) the liquid did not produce a purple colour, so no readily soluble proteins are present.

Boiling it in water has little effect. Frying it does not produce a Maillard reaction. Raw, it has a very slight sour taste and a firm texture and while not completely unpleasant, it is not something one would choose to eat unless there was nothing else available. It does not seem to take on flavours if cooked with other things. The major feature is the firm gelatinous texture. I found that mixing the grains with some sweet fruit syrup made it palatable but not exciting.

It is easy to think that this mushroom might be native to Australia, given the association with the indigenous people, but in fact it occurs in other places, particularly in China where it has been used in traditional medicine as an anthelmintic (anti-parasite drug). The mycelium has been produced in submerged culture and the active ingredient isolated. It is a metalloprotease that acts on some of the proteins in the parasites. This class of compounds is common in fungi, and the toxin from Chlorophyllum molybdites is a metalloprotease.

Considering that this sclerotium can remain in the soil for decades, it is perhaps not surprising that it might have some defence against insects that might seek to attack it. In my part of the world, termites are ubiquitous and they attack the karri timber that grows in the same area as the mushroom, but the sclerotia are untouched. Similarly, worms are common but they don’t eat the sclerotium. The fungus has been incorporated in some pet deworming formulations.

After chopping some of the sclerotium up in a blender during one of my experiments, I cast the excess material onto the lawn outside. A couple of days later I noticed some magpies pecking at it. I am not sure what attracted them but they seemed to think it was worth eating. I guess it may have sorted out any parasite problems they might have. I also guess this might be useful for treating chickens too. I think that birds are equipped with chitinase enzymes that might be required to digest this material. Which makes me wonder how the human digestive system handles this stuff.

In a 1977 paper titled “The edibility and possible zoochory of the fungus Polyporus mylittae” Nigel Sinnot mentions some taste tests on a batch of sclerotia that were dug up by a tractor. The conclusions were much like mine. He also mentions that on various occasions, for example as mentioned by Cleland, pieces of fresh sclerotium have been buried and kept moist in which case a fruiting body developed. (This is also known to occur with the sclerotia of Polyporus tuberaster, according to David Arora. ) He suggests that this ability to form fruiting bodies from fragments of the sclerotium may confer some advantage to the organism. He further suggests that wombats might be part of this picture, though this would not be the case here in Western Australia.

Examination of the structure of the fruiting body suggests that it is in fact the result of the fusing of a number of primordia into a single structure. This is illustrated in the image below. Note that the fertile surface runs right down to the soil interface. The section on the right is completely separate from the rest of the mushroom until it fuses at the top. This would tie in with the observation that pieces of sclerotium can be form fruiting bodies on their own.

Sinnot quotes J. H. Willis who doubted that the fungus ever fruited under ‘natural’ conditions. This differs from the mushroom Fomitopsis hartmannii (formerly Laccocephalum hartmannii) which sometimes makes an appearance on mushroom forums as growing from apparently undisturbed ground.

In a recently published book The Fungi of Kangaroo Island and Beyond, by the Pamela and David Catcheside, the authors show a fruiting body developing on an agar plate. I have little doubt that it could be cultivated in much the same manner as Morchella species and induced to form sclerotia.

A question that naturally arises is whether the fruiting body can be eaten. There seems to be no mention of this anywhere. I think that it would be rather a tough meal for the naturally occurring mushroom. It might prove more tender in cultivation. I taste-tested a small piece and it didn’t have any pronounced taste, though I thought I could detect a slight ‘soapy’ taste.

13 May 2025

Today I came upon a quote from George Augustus Robinson, Protector of Aborigines in Tasmania. It is in Tim Flannery’s book “The Explorers, p150. On 25 October 1891 he was travelling with a group of people from the Big River tribe. He says

“In our way the natives showed me a dead tree where there was native bread growing. I saw no signs of it myself; they smelt the wood and said that the plant was a long way in the ground. “

This account differs from what I have previously read, where they are reported to have poked into the ground with a stick and smelt that. Robinson’s account makes much more sense. It is entirely possible that the wood which is infected with the fungus would have a distinctive smell. Once this smell is detected in the wood, it is a matter of poking the ground to locate the sclerotium.

On the previous page he also says;

One of the native women, Sall, found a bulbous plant call by the white people ‘native bread’, which they gave to me as a present. From these accounts is seems that the sclerotia were in some abundance and that the natives were adept at locating them.

It would be an interesting exercise to see if a dog could be used to sniff them out by locating infected wood.