Melilotus officinalis can be an annual or biennial plant, and is 4–6 feet (1. 2–1. 8 m) high at maturity. Leaves alternate on the stem and possess three leaflets. Yellow flowers bloom in spring and summer and produce fruit in pods typically containing one seed. Seeds can be viable for up to 30 years. Plants have large taproots and tend to grow in groups. Plants have a characteristic sweet odor.