stool

The process of layering is well known: it consists in bending a young branch […] into the soil to a certain depth, and elevating the top part of it out of the soil in an upright direction; in time the buried part takes root, and the shoot becomes a perfect plant. The root which produces the young shoots for layering is called the stool. Stools are planted about six feet apart every way in a deep fresh soil. […] Stool. – The root of a tree which has been left in the ground, the produce of another tree, or shoot for saplings, underwood, &c.