1. If there is no cambium tissue between the xylem and phloem, it is called a closed collateral vascular bundle. Closed collateral vascular bundles are the identifying feature of monocots.
2. Cambium tissue between xylem and phloem is called free lateral vascular bundle. Free lateral vascular bundles are identifying features of dicots and gymnosperms.
3. If xylem is in the middle and phloem is located on either side, it is called bilateral vascular bundle. Equilateral vascular bundles are found in plants like gourd, pumpkin, cucumber etc.
4. If xylem and phloem form separate bundles, it is called aorial vascular bundle. If the number of auricular vascular bundles is less than five then the plant is dicotyledonous. If the number of auricular vascular bundles is more than six then the plant is monocotyledonous.
5. If the xylem is in the center and the phloem surrounds it, it is hydrocentric or amphicribal. Hydrocentric vascular bundles are found in plants like Lycopodium, Selaginella, Pteris etc.
6. If phloem is in the center and xylem surrounds it, it is called leptocentric or amphivesal. Leptocentric vascular bundles are found in plants like Dracaena, Yucca etc.