The intrusive growth of initial cells in re-arangement of cells in cambium of Tilia Cordata Mill.

Abstract

In the cambium of linden producing wood with short period o f grain inclination change (2-4 years), the intensive reorientation o f cells takes place. This is possible mainly through an intrusive growth o f cell ends from one radial file entering space between tangential walls o f neighboring file and through unequal periclinal divisions that occur in the ..initial surface” . The intrusive growth is located on the longitudinal edge o f a fusiform cell close to the end, and causes deviation of cell ends in a neighbouring file from the initial surface. Unequal periclinal division divides a cell with a deviated end into two derivatives, unequal in size. The one o f them, which inherits the deviated end. leaves the initial surface becoming a xylem or phloem mother cell. This means that the old end is eliminated. The intensity o f intrusive growth and unequal periclinal divisions is decisive for the velocity of cambial cell reorientation. The oriented intrusive growth occurs only in the initial cells. For that reason, changes in cell-ends position do not occur within one packet o f cells but are distinct between neighbouring packets.