Anatomy of a plant organ was observed. It shows presence of protoxylem towards centre and metaxylem towards periphery of organ; cambium is present between xylem and phloem.The plant organ is

In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ. This type of primary xylem is called endarch. In dicotyledonous 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. Hence the plant organ is dicot stem.