Distortion of teatree stems by twine as a means to determine the number of years that the stems have been used to support cannabis plants.

In New Zealand, stems of teatree (Kunzea/Leptospermum) growing around illicit cannabis plots have been used to anchor lengths of twine running through the plots to hold cannabis plants upright. Forensic examinations of distortions of teatree stems caused by the twine have been carried out to determine when the twine had been first tied around the stems, in order to estimate the number of years that plots have been in operation. In this experiment, baling twine was tied around stems of a teatree (Kunzea ericoides) and the effect monitored for a period of three years. Varying degrees of stem distortion occurred during the first year, caused initially by expansion of callus (a wound tissue) rather than constriction of the growth (annual) rings of the xylem. Although this callus has a type of growth ring, these are not annual, therefore cannot be used to determine the number of years that stems have had twine attached. Xylem growth rings of the teatree in this experiment were not restricted until the third year. Distortion of teatree stems allows the determination of a minimum (not absolute) number of years that twine has been attached.