''Ballota nigra'', black horehound, is a

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicina ...

of the family

Lamiaceae The Lamiaceae ( ) or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savo ...

. It is native to the

Mediterranean region In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and ...

and to central Asia and it can be found throughout Europe. It is also naturalized in Argentina, New Zealand, and the Eastern United States.Kew World Checklist of Selected Plant Families
/ref> It blooms in the Northern Hemisphere from May to August.

Description

''Ballota nigra'' has a very strong characteristic smell reminiscent of

mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

or humidity, and can be recognized by its clusters of hairy, reddish-purple flowers. It can grow up to 3 feet in height.

Morphology

Stem and root

It has herbaceous ascending stems, wooden and branched at bottom, covered by down folded hairs. The plant has a taproot system.

Leaves

Leaves are opposite and decussate, and range from oval-lanceolate to heart-shaped, with crenate or dentate border. Leaves, dark green and usually pubescent, measure 3–8 cm per 2–6 cm, and have 1–3 cm petiole. Upper face is wrinkled, with a net-like vein pattern.

Flowers

Flowers are organized in verticillasters, subspherical to about one-sided, with 15 to 30 flowers. Each verticillaster consist of two condensed dichasial cymes at axils of normal leaves.

Flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

has an actinomorphic calyx (length 9–10 mm, width 7 mm), made up by five

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined ...

s fused together in a tube with five teeths; and a labiate

corolla Corolla may refer to: *Corolla (botany), the petals of a flower, considered as a unit *Toyota Corolla, an automobile model name * Corolla (headgear), an ancient headdress in the form of a circlet or crown * ''Corolla'' (gastropod), a genus of moll ...

of 12–13 mm, ranging from pink to pale purple to withish. The corolla consist of a tube of about 6 mm and two lips; the upper one slightly concave (like a hood) and externally hairy; the lower one glabrous, with two minor lateral lobes and a major central bifid lobe. There are four didynamous

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s, running parallel under the upper lip, with glabrous filaments and yellow anthers.

Ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the bod ...

is superior, with a single white style and a 2-parted stigma. Below the calyx there are five filiform bracts, 8 mm long. Ballotanigra

Fruit

Each fertilized flower produces a tetrad of black nutlets, cylindrical to ovoid, 2 mm long, partially or fully covered by the calyx. The basal end is flat and attached to the receptacle, while the top end is rounded or pointed.

Biochemistry

''Ballota nigra'' contains diterpenoids like marrubiin, ballonigrin, ballotinone, ballotenol and 7-acetoxymarrubiin. Also, it contains phenylpropanoids.

Taxonomy and etymology

The plant was described by

Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, t ...

in ''Species Plantarum'' (May 1753). The name ''Ballota'' comes from the Greek ''ballo'' (to reject), because of the strong offensive odor of the plant; cattle will not eat it. The specific name ''nigra'' could refer to the black colour of dried leaves. The common name comes from the Old English words ''har'', meaning "downy or

hoary {{Short pages monitor