It is a grey-leaved herbaceous perennial plant, somewhat resembling mint in appearance, and grows to 25–45 centimetres (10–18 in) tall. The leaves are 2–5 cm (0.8–2.0 in) 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.
Horehound has been mentioned in conjunction with medicinal use stretching at least back to the first century BCE, where it appeared as a remedy for respiratory ailments in the treatise De Medicina by Roman encyclopaedist Aulus Cornelius Celsus. The Roman agricultural writer Columella lists it as a remedy for expelling worms in farm animals in his important first-century work On Agriculture. Since then, horehound has appeared for similar purposes in numerous herbals over the centuries, such as The Herball, or, Generall historie of plantes by John Gerard, and Every Man His Own Doctor: or, The Poor Planter’s Physician by Dr. John Tennent.
Several modern scientific studies have been conducted on the usefulness of horehound, apparently beginning to confirm what has long been folk knowledge. For example, a 2011 study concluded that the essential oil of M. vulgare contains potent antimicrobial and anticancer properties, while a 2012 study found marrubiin, one of the primary active compounds found in horehound, to possess "antidiabetic, anti-atherogenic and anti-inflammatory properties".
As an invasive weed
Horehound was introduced to southern Australia in the 19th century as a medicinal herb. It became a weed of native grasslands and pastures where it was introduced with settlers’ livestock, and was first declared under noxious weeds legislation. It now appears to have reached its full potential distribution.
It occupies disturbed or overgrazed ground, and is favoured by grazing because it is highly unpalatable to livestock. It may persist in native vegetation that has been grazed.
Horehound bug, a common insect that feeds on White Horehound
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (July 2009)|
- Zeid Zarai, et al. "The in-vitro evaluation of antibacterial, antifungal and cytotoxic properties of Marrubium vulgare L. essential oil grown in Tunisia", "Lipids in Health and Disease, 2011; 10:161"
- N. Mnonopi, R.-A. Levendal, N. Mzilikazi & C. L. Frost (2012). "Marrubiin, a constituent of Leonotis leonurus, alleviates diabetic symptoms". Phytomedicine 19 (6): 488–493. doi:10.1016/j.phymed.2011.12.008. PMID 22326550.
- Tennant, John (1727). Every Man His Own Doctor. p10.
- Everist, D.L. (1981) Poisonous Plants of Australia. 3rd edn (Angus & Robertson: Sydney). ISBN 0-207-14228-9
- Parsons, W. & Cuthbertson, E. (2001) Noxious Weeds of Australia. 2nd edn (CSIRO Publishing: Collingwood). ISBN 0-643-06514-8
- Jepson Manual Treatment
- Media related to Marrubium vulgare at Wikimedia Commons