Laticifer systems in Mandevilla illustris and M. velutina apocynaceae

Two Apocynaceae species from savanna (Cerrado) area of Sao Paulo State, Brazil were studied. In both Mandevilla species examined, the laticifer systems are of non-articulated branched type, characteristic of the family. In vegetative organs reported was the occurrence of a primary laticifer system of which the cells were differentiated in the embryo. However, additional laticifer cells were always produced during the growth of the shoot apex. A secondary laticiferous system produced by the cells of vascular cambium was identified in the tuberous root and in the stem. A proposed discussion on this apparently unique record in Apocynaceae was arisen to evaluate the main distinction between articulated and non-articulated laticifers.