ABSTRACT
A new model of the functional organization of the bark of Hevea brasiliensis was proposed. Most trunk tissue in Hevea is derived from the functioning of a lateral meristem, the vascular cambium which forms secondary xylem and phloem. In particular, its structure must adapt to the increased girth of the trunk, and the laticifers exploited for rubber production are differentiated in the phloem. Articulated, anastomosing laticiferous vessels form successive vertical networks called rings or mantles. The phloem also contains cells other than laticifers, including sieve tubes and companion cells. The wood is nonstoried; its axial system comprises isolated or grouped vessels of varying diameter, fibers, and vertical para and apotracheal parenchyma cells. The truly productive tissue in bark is thus the inner soft bark which lies between the cambium and the hard bark. At tapping, the bark is continually wounded and partly removed. Stimulation of Hevea is now common practice in plantations.
