Long ago I stumbled upon an image where a tree had multiple tumor-like growths all around it. This reminded me about myself. At the time I didn't pay much attention to it though.
More recently it has begun to interest me what exactly are these growths in trees, and other plants too.
Solitary Tree Tumor
Multiple Tree Tumors
I have since learned these are called tree burls and that they are considered valuable building material for wooden furniture.
In this study from 1958 the scientists are puzzled about the cause but Wikipedia tells me that
Ok, so why the heck am I posting this on Lipoma Board?A burl results from a tree undergoing some form of stress. It may be caused by an injury, virus or fungus. Most burls grow beneath the ground, attached to the roots as a type of malignancy that is generally not discovered until the tree dies or falls over. Such burls sometimes appear as groups of bulbous protrusions connected by a system of rope-like roots. Almost all burl wood is covered by bark, even if it is underground. Insect infestation and certain types of mold infestation are the most common causes of this condition.
The previous quote includes some interesting info. Tree tumors may be caused by an injury, virus, fungus, mold or even an insect infestation.
The definition of a tree burl is a hard, woody outgrowth, more or less rounded in form, usually resulting from the entwined growth of a cluster of buds. Such burls are the source of the highly figured burl veneers used for purely ornamental purposes. In lumber or veneer, a localised severe distortion of the grain generally rounded in outline.
Tree burls are always covered with bark, even if they are below the ground.
Burls are considered as benign and keep growing the life time of the tree. The growth has not been reported to start from the root tissue of the tree. They occur when a twig bud fails to grow normally, differentiating into the tissues needed for forming a limb, and instead just multiplies and multiplies and multiplies its bud cells. That's how you get the round growth with an irregular grain structure.
Many burls will sprout when placed into water, forming normal-looking shoots. Apparently the water saturation somehow helps them "remember" that they are, after all, limb buds.
Usually response to some sort of injury or invasion that triggers a response in the cells surrounding the area, causing unusual growth - a little analagous to cancer in animals but does not spread beyond immediate area and usually doesn't harm the tree, also a little analagous to scar tissue.
Does this sound familiar at all?
This is how a tree burl looks inside:
Here's another example:
And one more:
Oops, that was a lipoma there! Sorry, I got confused
So lipomas appear because of unknown cause. Genes do cause the tumor to form just like in the trees.
But what causes the genes to go crazy?
In the trees it seems there are various reasons. In lipomas - we simply do not know but most are willing to rule out stupid things like microbes and insects etc. It is simply impossible.
The above would make a nice ornament for some? Sorry, I couldn't resist myself.
Oh, did I mention that tree burls are contagious? It's very likely that if you find one you'll find another within 150 feet.