Cassia seed comes from cassia or jue ming zi, a plant that is native to tropical regions. The plant can grow as high as four feet (1.2 m), has yellow flowers and large leaves that group together with six leaves per group. It has pods that are about 20 centimeters (7.9 in) in length and contain the seeds, which are smooth to the touch and range from green to deep brown, sometimes with a yellow stripe.
The importance of the cassia seed is far-reaching, especially for those interested in Chinese medicine. It can be used for medicinal purposes, for dyeing, and even as an alternative to coffee. It can be found in many forms ranging from a whole seed to ground powders, tea packets, pastes, and herbal pillows.
The most popular use of cassia seed is for medicine. It's most commonly used to treat problems with the liver, kidney, intestinal, and vision. For example, it can be used to treat constipation and remove heat from the liver. Both cassia seed and cassia root can be made into a paste to treat ringworm and venomous snake bites. The seed can be used to treat blurry vision and irritated eyes too, and some people use it to lower blood pressure; however, people who are already taking medicine to control high blood pressure should not take cassia seed.