(1):

(n.) A genus of leguminous plants (herbs, shrubs, or trees) of many species, most of which have purgative qualities. The leaves of several species furnish the senna used in medicine.

(2):

(n.) The bark of several species of Cinnamomum grown in China, etc.; Chinese cinnamon. It is imported as cassia, but commonly sold as cinnamon, from which it differs more or less in strength and flavor, and the amount of outer bark attached.