Nature's Spray Paint: Inonotus glomeratus

I've never been able to pick favourites—be it a colour, a food, a flower, or a fungus. But I do have long lists of top contenders.

I have a particular soft spot for fungi that do something, that, in particular, show me process, whether it be life cycle or interaction with other Kingdoms or longterm movement through a landscape. Which is why it's a no-brainer for Inonotus glomeratus to make my fungi long list.

Here are the basics about Inonotus glomeratus:

• it's a polypore

• it can be found on a wide range of hardwoods 

• its fruiting bodies show either effused-reflexed or resupinate growth

• its spores are bright golden yellow 

• it is both parasite and saprophyte 

But what does it do?   

1. It Produces a Cool Optical Effect

Inonotus glomeratus is one of a many polypores that produces a "glancing" effect when the its pore surface is turned towards and away from light. When it catches the light the right way, it seems to flash silver.

This chunk of I. glomeratus shot from two different angles shows the
glancing effect on the pore surface. It's wickedly hard to photograph.

2. It Weeps Black Teardrops

Black, tar-like guttation droplets 

Well, they're not black teardrops; they just look like black teardrops...or blood...or tar. 

When the fungus is young and actively growing, it produces black drops of exudiate, or guttation (see my post on this phenomenon). Since I. glomeratus is usually resupinate and white to very pale grey at this stage, the black drops can be quite startling. The exudiate is often so plentiful that the ground beneath is splattered with pools of it. 

The contrast between the lightness of the pore surface
and the black guttation can be striking.

Guttation droplets can be so plentiful that they drip to the forest floor.

The droplets are sometimes reabsorbed into the fungus,
leaving negative drop-like pits.

3. It Paints Its Surroundings Yellow

It can produce copious amounts of yellow spores.

Not only does I. glomeratus produce ridiculous amounts of spores—on par with Ganoderma applanatum—its spores are an unusually bright yellow or sulphur. When there is little draught or wind near the time of maturation, this unassuming fungus can cover everything near it with with a yellow coating that looks exactly as if someone has gone overboard with a can of spray paint. It's a particularly eerie effect when it happens in woods you know no one else goes in.

These two shots were taken just a few days apart—the second, after a rain.

4. It Grows Whiskers

Close-up of Inonotus glomeratus pores showing setae, or hairs

Like most Inonotus species, I. glomeratus grows setae, which stick out of the pore surface like minute whiskers that are visible under magnification. Under the microscope these abundant setae look more like weapons than hairs.

Under the microscope, the hairs look vicious.

5. It Can Mimic Chaga

An I. glomeratus canker can look a lot like chaga. (Dianna Smith)

Another thing this extraordinary fungus does is produce sterile cankers that can look exactly like the infamous Inonotus obliquus canker, more commonly known as chaga. This happens in living trees, in its parasitic stage, after entering a living tree through a wound. Once it's gained entry, it causes a white rot of the heartwood. 

This knot is the likely entry point of I. glomeratus on this red maple.

Though I. glomeratus is most commonly found on maples and oaks, and is not uncommon on Populus, and can also be found on other hardwoods, including, I’ve read, on Betula, or birches.When it attacks maples, it does not normally develop a chaga-mimicking canker, rather it causes a prominent ridge of bark to grow around a rotten knot. Once this appears on a maple tree, (or a lumpy canker grows on another hardwood), there can already be a column of decay inside the tree 3 to 4 meters high. The fruiting bodies that produce the yellow spores are not produced until after the tree is dead.

6. It Can Confuse the Heck Out of Those Who Come Across It

I. glomeratus is a mushroom of many guises. It can be totally resupinate, sheeting a fallen log, or seriously pileate. Parts, or all of it, can be white, brown, orange-yellow, black, sulphur yellow, or grey. It can be covered with black guttation, or remnants of these drops, or it can have none. Its upper surface can be coated in golden or sulphur-coloured spores, or there can be no sign of yellow anywhere. Particularly when there are no spores or black guttation evident, it can leave people scratching their heads about its identity. The following selection of photos are all I. glomeratus.

References:

Inonotus glomeratus as a pathogen of sugar maples:

Inonotus glomeratus on Mushroom Observer