Roy wrote:

I have always been told its a certain species of Poppy that is used to
produce the drugs, that in general it would be hard or impossible to
do with the variety found in most countries. Any truth in that?

I researched this point while considering medicinal plants to grow.

All the true poppies have opiates in them, one strain has less of the
types that make people sick. Removing those other opiates is not
practical.