Plants With A " Memory "...

When attacked, many plants produce chemicals to ward off their attackers..
New Scientist magazine reports that some also form a " memory "
of the attack , allowing them to begin producing the repelling toxins more quickly if attacked again.

A cater pillar chewing on a tobacco leaf triggers the manufacture of
jasmonic acid , which travels to the roots.

This initiates the production of nicotine,
which returns to the leaves to make them undesirable to the eater.
Planets with roots previously exposed to the acid reacted more quickly
to the attack...

" This suggests that plants do indeed have a memory,"
says Ian Baldwin of the State University of New York at Buffalo..