In plants with secondary growth, the vascular cambium, originating between the xylem and the phloem, forms a cylinder of tissue along the stem and root.

• 而在双子叶和单子叶植物的排列又有所区别。中柱鞘是初生分生组织。它是侧根，木栓的发源。同时，根的次级生长，主要是维管束的次级生长，也是中柱鞘运动的结果。