Friday, March 3, 2006
Biodiversity Corner Artist's Conk
Fungal excitement! Rarely do I need a yardstick to measure a mushroom, but on February 18 I found the largest artist's conk that I have ever seen. It was 24 inches by 17 inches. I almost conked out. The Audubon Guide says they can reach 20 inches, and other books top them out at 26 or even 29 inches. They tend to grow on the lower part of hardwood trees and stumps. This huge one is only about two or three inches above the ground and it's a miracle that it hasn't been stepped on and broken by deer. It could have become a brokeback mushroom.
Name: The artist's conk is a polypore with the scientific name Ganoderma applanatum. Ganoderma means shiny skin and applanatum means flattened. Other members of the genus Ganoderma have very shiny skins — like Ganoderma tsugae, the hemlock varnish shelf and Ganoderma lucidum, the varnished conk a.k.a. Reishi or Ling Chih, well known in herbal medicine. The artist's conk has a much less shiny skin than these other species and is often covered with brown spores giving it a dull powdery surface.
Polypores: There are two large groups of mushrooms in which the spores are produced in tubes rather than on gills. When you look at the lower surface of this kind of mushroom, you will see many pores which are the open ends of the tubes. If the mushroom cap is soft and fleshy and looks like a typical cap-and-stem mushroom, it is referred to as a bolete. The porcini mushroom is a good example of a bolete. If the mushroom is hard or tough, grows on wood, and is not a typical mushroom shape, then it is called a polypore. The artist's conk is a good example of a polypore.
Wood decay: Most polypores decompose wood. The ones that break down cellulose and leave behind the brown lignin are the brown rot fungi. Those that break down lignin and leave behind the white cellulose are white rot fungi. The artist's conk is a white rot fungus which attacks both the heartwood and the sapwood. Some of the trees that came down in the recent gales may have been felled by Ganoderma applanatum.
Where found: Smaller artist's conks, up to six to eight inches, are very common on dead and dying hardwood trees. They sometimes turn up on conifers and sometimes there are many on a single tree. There are five or six on an oak along the Poole swamp trail, and some on a fallen birch at the Cranberry Bog. There are several around town on trees at the side of the road.
Distinguishing characteristics: The artist's conk is a fan-shaped bracket mushroom that grows on the sides of living and dead trees. It can be flat and shelf-like or somewhat curved and hoof-like. It is hard and woody. The upper surface is whitish, gray or brown and has concentric lines and ridges. It may also have hairline cracks. The lower surface is white and the spore-bearing tubes are packed so tightly — about four or six per millimeter — that you can hardly see the individual pores.
Longevity: Mushrooms are renowned for being ephemeral but some, like the artist's conk, last not only all season but for many years. New layers of spore-bearing tubes are added over the previous layers and separated by a thin brown line. If you cut a vertical slice through the conk, you can count the layers.
Scratch pad: The mushroom is known as an artist's conk because lines scratched on the white undersurface turn brown and hold the color permanently. Artists take advantage of this to create elaborate drawings. If you Google ganoderma art, you will find lots of examples. The photo shows a beetle (Goliathus orientalis from Zaïre) drawn on an artist's conk by Marian Adams of Lincoln. Less gifted people scratch simpler designs. I looked under one in the woods one day and read "Hi."
References: Tom Volk, professor of Mycology, U. of Wisconsin, http://tomvolkfungi.net/; David Arora, Mushrooms Demystified; Gary H. Lincoff, Audubon Field Guide to Mushrooms of North America.
Submissions are encouraged from everyone. You can write the column or tell me what you saw and I will write it. The only requirements are that the species exists in the wild and was seen in Carlisle. Send a note to Kay Fairweather at email@example.com
© 2006 The Carlisle Mosquito