Horehound, sometimes called white horehound, is a member of the mint family that thrives in pastures and other wayside places all over Europe, Asia and parts of Africa, although it is now naturalized in North America and elsewhere. The herb was well known to the ancient Romans and Egyptians, the latter of whom called the plant Seed of Horus or Bull's Blood. Because the plant is considered one of the bitter aromatic herbs, it is often found in natural syrups and lozenges, sometimes in combination with marshmallow, mullein or licorice root. Horehound is also used in herbal tea blends and to make liquid extracts.

a bit of botany

a little botanical information on horehound

description
Marrubium vulgare is a flowering plant in the Lamiaceae or Mint family. It is a gray-leaved herbaceous perennial plant, somewhat resembling mint in appearance, and grows to 25–45 cm tall. The leaves are 2–5 cm long with a densely crinkled surface, and are covered in downy hairs. The flowers are white, borne in clusters on the upper part of the main stem.

common names & nomenclature
Its Latin name of Marrubium is said to be derived from Maria urbs, an ancient Italian town. Others believe the name derived from the Hebrew marrob which means "bitter juice".

Also known as:
white horehound, common horehound, seed of hours, bull’s blood, eye of the star, hoarhound