xylem is surrounded by phloem, phloem is surrounded by xylem, xylem and phloem occur on the same radius, xylem and phloem occur on the different radii" /> xylem is surrounded by phloem, phloem is surrounded by xylem, xylem and phloem occur on the same radius, xylem and phloem occur on the different radii" /> xylem is surrounded by phloem, phloem is surrounded by xylem, xylem and phloem occur on the same radius, xylem and phloem occur on the different radii" />