
Morphine is the most important alkaloid in opium, an extract of the poppy Papaver somniferum. A good grade of opium contains 9–14% of anhydrous morphine. It has been used as a potent painkiller for more than 150 years, especially after the development of the hypodermic needle. But it is extremely addictive and withdrawal is difficult.
More about this molecule from CAS.