Fig. 2

Manual segmentation of a knot in oven-dried state with ImageJ and “Gourmands” plug-in (on the left). The plug-in allows putting markers in the 3D space for delineating the stem pith and both sides of knots. The end of an outgoing knot (i.e., the knot/branch boundary) was fixed as much as possible at the “triple point” where stem wood meets knot wood and bark. 3D representation of the knot (on the right)