Shoot meristem organisation

Shoot apices (meristems) in higher plants are multicellullar and multilayered
  • most dicots: 3-layered apices:
    • 2 tunica layers (L1 and L2)
    • 1 corpus (L3)
  • monocots: 2- or 3-layered apices

Normally an orderly cell divison planes prevents the mixing of these cell layers

multilayered apex



Each shoot apical cell layer makes a
predictable contribution to the plant:

L1
  • leaf epidermis
  • stem epidermis (incl. thorns)
  • flower epidermis
L2
  • pallissade parenchym
    and margin of the leaf
  • gametes
  • petals
  • stem
L3
  • spongy parenchyma of the leaf,
    veins
  • roots
  • central part of the stem