A Punk Knot - Of Course!
One of the most interesting aspects of my job as Department ombudsman is that citizens will share with me unusual observations and objects from the natural world. This happened a couple of weeks ago when a gentleman from Arnold, Mo., sent me a photo of something he found in the woods of Washington County while turkey hunting.
From the photo, I first thought it was an insect gall from an oak twig. The gouty oak gall is formed when a small wasp lays its egg in an oak twig. The oak responds by producing a growth of woody tissue to encapsulate the egg. Eventually the egg becomes an adult insect and leaves the woody gall. The only problem with my diagnosis was that the object in question was 5 inches across and the gouty oak galls only get as large as about 2 inches across.
I offered to seek a better answer with the object in hand, and it was mailed to me shortly thereafter. Being able to hold the mystery item did not give me much insight into what it was. It did seem woody in some areas and was rough-textured and furrowed like bark, but it was softer and more pliable in other areas. It somewhat resembled a puffball fungus, but the hard tissues did not seem to fit a puffball. While fighting back visions of alien creatures bursting from my chest, I sent it to the real expert, the Department’s forest pathologist in Columbia.
The answer came back that it was definitely a fungus rather than a wooden object. It is a type of canker called a “punk knot.” In this case “punk” refers to poor quality wood resulting from decay. The punk knot forms on tree trunks that have internal areas of rotting tissue. It develops at the site where a branch stub or wound lets the fungus enter the trunk. It is thought that the punk knot allows air exchange into the decaying area of the trunk so that the decay can progress. The one that I was mailed had apparently fallen from a tree. Had it remained attached to the tree trunk, it would have looked like a bark-covered canker on the trunk and probably would have gone unnoticed.