Definition for Saint-John’s-wort

From Biology Forums Dictionary

St. John’s wort is a plant with yellow flowers whose medicinal uses were first recorded in ancient Greece. The flowering tops of St. John’s wort are used to prepare teas, tablets, and capsules containing concentrated extracts. Liquid extracts and topical preparations are also used. Today, St. John’s wort is used by some for depression, anxiety, and/or sleep disorders.