Hyptis suaveolens



Hyptis suaveolens

(L.) Poit. 1806

pronounced: HYPE-tiss swah-vee-OH-lenz

(Lamiaceae) — the lavender family)


common name: horehound, mint weed, pignut

Hyptis comes from the Greek 'υπτιος (hyptios), turned back, referring to the lower lip position of the flower; suaveolens is Latin for sweet-smelling.
This shrub or woody herb from tropical America is now widespread through most of the tropics as a weed. It grows up to about 1.5 m tall, with hairy stems that are square in cross-section.

The leaves have a strong smell when crushed. They are ovate to obovate, 3 – 5 cm long and 2 – 4 cm wide, the margins serrulate, the lower surface densely hairy, and the petioles up to 3 cm long.

The plant produces flowers at the early age of 2 or 3 months. The flowers, which have 4 stamens, are in small cymes along branch ends with reduced leaves. The calyx is about 5 mm long in the flower, 1 cm in the fruit, and ribbed. The corolla is bluish. The flowers have a large number of pollinators, and this leads to enormous seed production.

The fruits are nutlets about 1.2–1.5 mm long, slightly notched at the ends. The seeds are protected in a spined burr, and this helps greatly in their dispersal. They remain in the bristly fruit, which easily attaches to fur and clothing, and can be dispersed by water as well.. The mucilaginous coating of the seeds, when wet, will also adhere to potential vectors.

Horehound seed is often a contaminant in pasture grass seed. The seed can remain dormant for many years until the right conditions for growth occur.

The plant favours dry, open locations, on roadsides, or in disturbed or overgrazed areas, by watercourses, and in pastures and open forests where the soil is well-drained. It can form dense thickets. It is considered dangerous to livestock.

In India, where the plant is well-established and is becoming an invasive species, it is used medicinally as a treatment for indigestion, stomach pain, nausea, flatulence, colds, and infections of the gall bladder. The essential oil the plant contains has antibacterial and antifungal properties. Besides all this, the plant has insecticidal properties, and is said to be a mosquito-repellant. Its rapid spread, however, not only inhibits other nearby species, but increases livestock pressure on the native species because the animals find this plant unpalatable due to the essential oil. Its disadvantages as an invasive weed far outweigh its medicinal benefits.


Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.


Photographs taken in Picnic Bay 2009, 2012, Nelly Bay 2013, Horseshoe Bay 2014
Page last updated 16th January 2019