A processing head (10) for a forestry machine (1) is intended to process a tree (9) having a trunk (92) with a longitudinal direction (90), branches (94) extending from the trunk (92) transversely to the longitudinal direction (90) and knots (96) extending into the trunk (92). The processing head (10) comprises: a frame (2) having a seat (20) for receiving the trunk (92) of the tree (9) to be processed; a motorised device for moving the trunk (92) relative to the seat (20), by advancing the trunk (92) through the seat (20) along the longitudinal direction (90) of the trunk (92); one or more blades (26) for cutting the branches (94) from the trunk (92) as the trunk (92) advances; a detection system for detecting positions of the branches (94) and/or of the knots (96) on the trunk (92) as the trunk (92) advances. Information on the positions of the branches (94) and/or of the knots (96) is processed to determine an identification code that is based on said positions and that refers to said trunk (92) or to a segment obtained from said trunk (92). The identification code is comparable against a code determined a posteriori for a specific trunk or for a specific segment of trunk, in order to establish whether the specific trunk or the specific segment of trunk corresponds to said trunk (92) or to said segment of trunk (92). The information on the positions of branches (94) and/or of knots (96) can also be used to determine, during a processing of the tree (9), one or more positions on the trunk (92) in which to cut the trunk (92) perpendicularly or transversely to the longitudinal direction (90), which is to say to optimise the truncation of the trunk (92).