Induced Disruption of Sieve Element Plastids inHeracleum mantegazzianumL.

Abstract
Sieve element plastids of Heracleum mantegazzianum L. were disrupted in fresh tissue by treatment with iodine. Their breakdown and the consequent release of starch grains into the sieve element lumen was recorded by cinémicrography. We discuss how plastids burst to release the particles so frequently seen in sieve tubes under the light microscope.