Which of the following is a characteristic of morphine?

Morphine is indeed the principal constituent of opium, which is the dried latex obtained from the opium poppy. This characteristic highlights morphine's natural origin from opium, making it a key substance in the study of narcotic analgesics.

Additionally, morphine's legal use is heavily regulated, primarily being confined to medical settings such as hospitals where it is used for pain management, especially for patients suffering from severe pain conditions. This limitation underscores the potential for misuse and the need for controlled distribution of such a potent substance.

Morphine is also known for its physical properties—it is typically odorless, has a bitter taste, and can darken over time due to exposure to air or light. These characteristics are important in understanding how to handle and store morphine safely.

Given that all these statements accurately describe morphine, the most comprehensive answer encompasses all of these attributes, confirming that each aspect contributes to understanding what morphine is and how it is categorized legally and physically.