Armillaria ostoyae

The darker side – Dark Honey Fungus

Following on from my previous post covering the Honey Fungus, I felt the need to feature this common and equally destructive Armillaria species. Again, it’s cap is variable and looks very similar to the standard Honey Fungus, but with a few distinctive visible differences.

Dark Honey FungusThe Dark Honey Fungus (Armillaria ostoyae), like A.mellea, often grows in large, clustered groups on or around deciduous and coniferous tree stumps, logs or even shrubs. It can fruit early, in the summer months and continue to do so up until early winter. Sometimes it appears as if growing on soil or grass, but they are actually fruiting from dead roots underneath the soil.

At first glance, the Dark Honey Fungus looks pretty much the same as the Honey Fungus as it has similar cap colouring, ranging from yellow-brown to dark brown, although they are more often darker brown. As mentioned, shapes are a little variable, with some rounded and others wavy and/or with a central depression or shield shaped. This is dependent on age also. Caps can also grow slightly larger; up to 15cm across.

The scales (or fibrous flecks) on the cap surface are much more prolific at the centre, and are a much darker brown. A decisive key difference when compared to the A.mellea can be seen on the bottom/edge of the ring, high up on the stem. If you look closely, there are dark brown markings at the edge whereas they would be pale yellow on A.mellea. So take a close look as this will aid in identification.

Safe to eat?

Most consider this fungus edible but must be cooked well and only a little tried first as it can cause stomach upset for some people. Because of this, some experts believe it to be poisonous and not worth trying.

Strange but true!

And just before I sign off, here’s an interesting titbit for you; A new record holder for the title of the world’s largest known organism was recently discovered in 1998. It was actually a Dark Honey Fungus (Armillaria ostoyae) covering approximately 2,384 acres of soil in Oregon’s Blue Mountains, USA. Based on its current growth rate, the fungus is estimated to be 2,400 years old but could be as ancient as 8,650 years, which would earn it a place among the oldest living organisms as well. Fancy that!

Images of Armillaria ostoyae

Dark Honey Fungus – Armillaria ostoyae. Notice the dark brown flecks covering the cap (densely packed at the centre) and the dark markings on the edge of the whitish ring.

QUICK ID TABLE: DARK HONEY FUNGUS Armillaria ostoyae

CAP / FLESH

3-15cm across. Variable shaped; rounded to shield shaped. Covered in dark brown fibrous fibres/flecks.

STEM

6-15cm x 0.5-1.5cm. Whitish/Yellowish. Darker reddish towards base. Whitish ring with dark markings at edge.

GILLS / SPORE PRINT

Initially white, then yellowish, then pinkish/brown with darker spotted areas.

Spore Print: Pale cream (see how to take a spore print here).

HABITAT / SEASON

In clusters on or around stumps and trunks of deciduous and coniferous trees & shrubs. Summer to early winter.

EDIBILITY

Debatable. May cause gastric upset in some. Must be cooked.

The Genus ARMILLARIA (Honey Fungus): Characteristics to look out for:

• Medium to large fruiting body in large tufted groups, fused together at the base.

• Yellow-brown, Orange Brown, Dark brown colours / Round, Shallow domed to wavy shapes.

• Dark flecks or small scales on cap head, especially at the centre.

4 replies
  1. Bill Head
    Bill Head says:

    I would like to thank John for his help in identifying a fungus growth that appeared very suddenly at the base of our apple tree. As someone with no experience of fungi/mushroom, John’s knowledge was invaluable to me. I now know that the garden has been invaded by honey fungus! Many thanks for an excellent web site.

    Reply
  2. Yaroslav Kolodiy
    Yaroslav Kolodiy says:

    This fungus is very popular for harvesting in Russia & Ukraine. I ate kilograms of it over my life, and harvested many buckets. If young & healthy, can be dried, but not very good for drying. Very nice pictures!

    Reply

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