Simple botanical name Senna (SEHN-uh) is mysterious and unusual, yet sounds familiar. It has the simplicity of Jenna, but the uniqueness of Gwenna. It can be shortened to Sen, which means "one thousand" in Japanese. (Japanese parents bestowing the name Sen upon their child intend the meaning as "to live one thousand years". It can also refer to the sennin forest/mountain hermit. I named my first cat this, and she definitely suits the name.) The senna plant, specifically the Senna Alexandrina, is a flowering bush with little yellow flowers and can be found in the tropics. Lately it can be found as an ingredient in dieter's tea, laxative tea, although it has a wide array of uses. In Arabic the name means "brilliance."
This name has been used in a few books and movies, one of which being a vampire in the Twilight series, the other a girl in K. A. Applegate's Everworld book series.