The present study is aimed to study the effect of exogenous growth regulators on secondary vascular differentiation in Hibiscus cannabinus and Hibiscus sabdriffa herbaceous species belonging to family Malvaceae and Kigelia pinnata a tree species belongs to family Bignonaceae. Study on the effect of IAA, NAA, GA, BAP and Ethephon on vascular differentiation of these two plants. First chapter deals with application of growth regulators on stem and seedlings of Kenaf. Second chapter covers in vivo hormone treatment to stem of Kigelia pinnata on growing twigs and dormant twigs.Third chapter describes role of media used and growth regulators on vascular differentiation and lignification of cell walls. The major impetus behind development of this protocol was to allow further studies of vascular development, outside the confounding influences of other parts of the tree. Fourth chapter outlines the ultrastructural changes associated with cell wall and lignification following application of growth regulators.