 Morphine is the principal alkaloid in raw opium and constitutes roughly 8–19% of opium by dry weight (depending on growing conditions).Some purpose-developed strains of poppy now produce opium that is up to 26% morphine by weight.A rough rule of thumb to determine the morphine content of pulverised dried poppy straw is to divide the percentage expected for the strain or crop via the latex method by eight or an empirically determined factor, which is often in the range of 5 to 15.