Describe Formation of Secondary Medullary Rays

Formation of secondary medullary rays:

i) Secondary medullary rays are formed from the cambium ring.

ii) The cells of same particular places of a cambium ring produce parenchyma tissue instead of xylem or phloem.

iii) The narrow bands of parenchyma tissue run radially through secondary xylem and secondary phloem tissues.

iv) These narrow bands of parenchyma tissues are known as secondary medullary rays.

Secondary medullary rays may be differentiated into xylem medullary rays and phloem medullary rays


  • Secondan Xylem medullary rays: Lateral conduction of raw food materials.
  • Secondary Phloem medullary rays: lateral conduction of prepared food materials to xylem and phloem tissues respectively.