Tall trees and Mushrooms

One very common mushroom throughout the SW of WA is a species commonly known as Hydnum repandum. It differs from normal mushrooms in that it has spines instead of gills or pores.

It can be found in open marri/jarrah forest in hills around Perth, but down here I find it most frequently in association with tea-tree (Taxandria) scrub on my property. Like the Chantarelle, it grows in rings.

It is a relatively long lasting mushroom, not prone to insect attack or rot. Though small, it is not hard to pick enough for a meal or two in half an hour if you are in the right area.

Here is a plateful that I picked one day.

A favourite dish I make with these involves putting them into a pan with some chicken stock and red wine and reducing the volume to about half. Then chicken can be added, along with vegetables and some cream to finish.

A close-up of the mushroom is shown below, but the colour leaves something to be desired.   I will try to get a better one this season.

These also occur on the east coast where they are reported to grow in Messmate forest in Victoria.

There is another very similar species or perhaps variety that grow in close proximity to these ones.  They have been described as Hydnum ‘chestnut’ or Hydnum aff. repandum.  These ones have a longer stem and a chestnut brown cap.  I have also eaten these and they taste similar though they are not as robust in form as the orange toned species.  This one also grows in Victoria and Tasmania.

Both of these forms can exhibit a deep pore at the centre of the cap.  I did wonder if this was Hydnum umbilicatum, but Roger Hilton advised me otherwise and since this feature appears to be randomly distributed in specimens of both types, it is most likely a morphological variation rather than a separate variety or species.

Note: August 2016

Some recent DNA information from suggests that the chestnut variety is Hydnum crocidens.  It is interesting then to see the similarities between these mushrooms and those on Clive Shirley’s NZ site that are named as varieties of Hydnum crocidens.

It is even more interesting to read a recent  phylogenetic analysis of Hydnum based on DNA analysis and published in May 2016.  This puts paid to any concept that this mushroom is Hydnum repandum.  Specimens in the WA Herbarium are of un-named species (17 and 19) and others are unequivocally Hydnum crocidens.  The 3 species from New Zealand are all found in Australia. 

The name ‘crocidens‘ derives from mycologist Mordacai Cooke, who described them in 1890.  Below is a brief excerpt from his 1892 book ‘Handbook of Australian Fungi’, together with his illustration.

Species fungorum (Oct 2022) says that the current name for H. crocidens is H. ambustrum, described by Cooke and Masse slightly earlier in 1887.

Under the microscope, the spines appear glistening white with some of them displaying an orange-coloured point. There is some suggestion from this image that the spines are hollow.

The spores of this species are very small and almost spherical. My sizing is slightly larger than that reported by Cooke.

The spores are borne on basidia that are normal to the surface of the spines. From what I can make out there appear to be 5 spores on each basidium.

It is noticeable that these mushrooms are resistant to decay. They can last for many weeks in the wild without developing the fungal infections like Hypomyces that cause the rapid demise of other species. This suggests that they have some inherent antimicrobial activity.

A remarkable example of this resistance is shown in the images below. These specimens were collected on 7 August and this photograph was taken on 24 October, which is a period of 78 days. They have been kept in an ordinary refrigerator in a plastic zip-lock bag. There is not the slightest visual hint of decay nor any odour. I would expect most mushrooms to be significantly degraded over this period.

Medicinal use of Hydnum.

Recent (2021) research has shown that extracts from Hydnum have antibiofilm activity. This is important because many chronic bacterial infections, such as the childhood ear infection Otitis media rely on the formation of a biofilm for their persistence and their resistance to antibiotics. While this research is behind a paywall, the abstract suggests that extracts of the mushroom used in conjunction with antibiotics can resolve biofilm infections.

Some components of the mushroom include the two very closely related flavinoids myricetin and apigenin. The structures of these are shown below.

These two compounds are the subject of a lot of publications. As an example, myricetin has recently been reported to have potential as an anti-viral and anti-inflammatory agent with potential to be useful in the treatment of Covid-19.

There are anecdotal reports that consumption of Hydnum as an uplifting effect on mood. I have not observed this effect personally.