Abstract
Two types of wavy grain were found in the xylem from Aesculus stems: with long (500 mm) and short (6 mm) waviness superposed on spiral grain. On radial splits the ridges of long waviness ran obliquely up the stem from the pith to the cambium on the average at a 5° angle with the stem axis. On the other hand, the short waviness ran down the stem from the pith to the cambium at an average angle of 86° with the stem axis. Investigation of the orientation of cambial events on the basis of splitting and uniting rays in the successive terminal xylem layers demonstrated that domain patterns in the cambium are responsible for the wavy grain.