Closed vascular bundles lack

Closed vascular bundles lack cambium . In dicot stems , cambium is present between phloem and xylem . Such vascular bundles because of the presence of cambium , possess the ability to form secondary xylem and phloem tissues and hence, are called open vascular bundles . On the contrary, vascular bundles in monocots have no cambium . hence , they do not form secondary tissues, and are referred to as closed.