If he knew..

[Eruanna]

Originally posted by Makar

In the films, it seems PJ tried his hardest to make it marijuana

I too had a sense of this. Mainly in the scene when Merry and Pippin greet the others at Orthanc after the Battle of Helm's Deep ('Flotsam and Jetsam') although it's obvious that they have been drinking they seem to put their rather dizzy behaviour down to pipeweed.
Also, in the scene where Pippin goes off to Minas Tirith with Gandalf, Merry is very concerned that Pip is smoking too much. Surely a sign that smoking too much weed is detrimental to one's health?