A preliminary examination of Cordyline plants indicated that this was a difficult material for investigating the influence of hormones on the cambial activity because (a) the plants do not form annual growth rings, making it difficult to measure the amount of new accumulation of the secondary tissue
produced after the treatment of the meristem with growth regulators, (b) the growth rate of this plant is much slower than one of the dicotyledonous twigs and, therefore, the experiments with growth regulators take much longer and are more prone to the risk of tissue infection (Fisher & Tomlinson, 1972; Fisher, 1973).
Such an incident requires a replacement surgery, which causes significant secondary tissue
loss, according to graduate student Nisarg Shah.
Plants that grow for a relatively long time, and particularly those that survive the winter, do so as the result of lateral meristem, regions of meristematic activity that cause a plant stem or root to increase in diameter and give rise to secondary tissue
. By far, the most important lateral meristem is the vascular cambium, a cylinder of cells in the roots and stems of woody plants that give rise to secondary xylem or phloem.
The secondary tissue
formation begins with radial elongation of the vascular bundles which is predicated on a series of periclinal cell division of the intrafascicular cambium (Fig 1C).
The C[O.sub.2] laser is known to induce secondary tissue
reactions, and its use leads to slower wound healing because of several well-known factors, including carbonization, thermal necrosis, inflammatory cell infiltration, lack of platelet aggregation, and loss of biologically active factors.
Free radicals are known to contribute to amplification of SCI by causing direct damage to tissue and by promoting inflammatory processes that cause secondary tissue