Saturday, June 26, 2010

Woody Bracket Fungus

Ganoderma australe
I photographed this beautiful bracket fungus, on a dead tree-stump at the Bunya Mountains, yesterday. Isn't it a lovely?
The brackets of this species of fungus may last for 10 or 15 years, and renew themselves annually with a fresh, white, spore-producing layer like the one shown here. It coats the rim, covers the underside, and drops fine, red-brown spores. You can see in the photo that they are so plentifully produced as to have covered the leaves below with a dusty-looking layer. The rim fades to brown over the year, and will be covered with another new layer around this time in 2011.
These enormous bracket fungi feel woody to the touch, and rapping on them with the knuckles makes a sound like knocking on a door.
Brackets of this kind, like mushrooms and toadstools, are “fruits” which reveal the presence of the hidden body of the fungus. The body called the “mycelium”, consists a network of white, thread-like “hyphae”. In the case of a partially-decayed stump like this one, the mycelium would be well-established throughout the dead wood, busily engaged with its important job of decomposing it. The nutrients which are released, as the old wood decays, will be taken up by new, growing plants. Some of these will be new trees to replace this ancient corpse, but even the nettles in the photo, lovers of fertile soil, are enjoying the benefits provided by the fungus.
Ganoderma australe is native to tropical and sub-tropical countries around the world, reminding us that “australe” means “southern” (not “Australian” as is sometimes assumed.) It actually occurs in the more northerly parts of Australia. A great deal of the world’s botanical science has been done from a Northern Hemisphere perspective!
I once had one of these lovely fungi growing on a dead tree-stump in my garden, and was disappointed when my neighbours’ children knocked it off. I have discovered, since then, that this species of fungus may not live on dead wood alone so have become less keen on it as a garden resident.
There are many kinds of fungi that can eat the centres out of living trees. The heartwood - the best and strongest timber in the centre of the tree - is no longer alive, so is fair game to anything that eats dead stuff. This makes fungi unpopular with anyone who is growing trees for their timber, but popular with the many species of wildlife that need the fungus-created hollows for survival. Trunks shaped like hollow pipes can actually be stronger than solid ones, so these fungi can actually prolong the life of trees, too.
Apparently there is some doubt about whether this fungus species really does harm the sapwood, which is the living, growing part of the timber surrounding the heartwood. It colonises wounds in sapwood, but the jury is still out on whether it has any responsibility for killing living tissue. If it does, however, it would certainly do the trees no good at all!

No comments: