This section is from the book "The Gardener's Monthly And Horticulturist V21", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
On a street of this town a paper mulberry attracted my attention by reason of an unusual development of roots; that is to say, it was an unusual sight to me, though it may be of common occurrence. The interior of this tree, a medium sized one, was completely filled with decayed wood, much of which had become quite black and was therefore in a suitable condition to receive and support root growth. New wood had covered the edges of the broken side through which the rotten interior was seen, and from this new formation, roots, in one instance an inch or two in thickness, had struck down into the mass of soft decayed matter, the roots being almost equal in quantity to the supporting material. The starting point for many of these roots was three or four feet from the ground, but whether they issued from the entire interior surface of the tree, or only from the new wood at the edges of the opening, I cannot say.
This instanced fact simply shows that under different stimuli different results are produced from the same surface of wood. If the conditions are favorable for the growth of leaf buds such will be produced; if for roots, they will naturally follow.