BLACK HOREHOUND

Ballota nigra

Mint / Dead-Nettle Family [Lamiaceae]  

month8jun month8june month8jul month8july month8Aug month8sep month8sept

status
statusZarchaeophyte
 
flower
flower8bicolour
 
flower
flower8purple
 
inner
inner8white
 
inner
inner8black
 
morph
morph8zygo
 
petals
petalsZ2
 
type
typeZtieredwhorls
 
stem
stem8square
 
smell
smell8pong smell8pongs smell8awful smell8stinks smell8nauseous smell8foetid smell8pungent
pongs

7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
Standing upright up to a metre tall. Flowers in separated whorls up the top half of the stem, and un-like Wild Basil, the stalk is entire and doesn't start afresh above each whorl.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
Flowers pink to purple with two lips. Green parts often turn a dirty purplish-black, hence the common name.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
Stalk often reddish-brown. Sepal tubes green becoming purplish-brown towards the five-pointed tips. Sepal tubes often barren with no flower.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Sometimes the whorls are well separated on an entire, square and hairy stem. Sepal tubes have long thin, narrow bracts visible just underneath the whorls.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
Upper lip of flower is entire and very hairy.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
Lower lip of flower has four lobes, the two central being longer. Whorls often crowded towards the tip of the stem. Also, un-like Hedge Woundwort or Marsh Woundwort, the whorls are dense often two or three layered.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
The stem is square, the leaves toothed with prominent ridges.


7th July 2005, arable field edge, Helsby, Cheshire Photo: © RWD
The upper lip of the flower appears frayed, but these are actually dozens of whitish hairs. Most sepal tubes are sterile and bear no fruit after flowering.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Flowers are pink/purple with white mostly longitudinal markings.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Flowers in two parts, the upper hood is very hairy; the lower lip much longer with two side-lobes and a lower lobe which parts into two roundish lobes.


6th Sept 2015, dunes, Hightown, Sefton Coast. Photo: © RWD
Here comes another example.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
The sepal tubes are funnel-shaped. The sepals bracts behind them have extremely long narrow wire-like teeth.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Showing the very long narrow sepal teeth just behind the sepal tube.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Leaves bluntly and shallowly lobed.


26th Aug 2013, ex-industrial land, Marshside, Sefton Coast. Photo: © RWD
Sepal tube by transmitted light showing 10 ribs and the purple-tinged five-star opening.


Some similarities to: Motherwort but the leaves of Motherwort are very different, having three lobes.

Not to be semantically confused with : Hound's-tongue [a plant with similar name]

Not to be confused with the closely related species: White Horehound (Murrubium vulgare) which is in a differing genus (within the same family), thyme scented and is so smothered in white hairs as to appear grey-green.

Many similarities to Hedge Woundwort but that has deeper purple flowers with white markings on the lower lip, which is also not lobed as conspicuously as is Black Horehound. Also, Hedge Woundwort has no sterile sepal tubes; all will have flowers in them. Black Horehound has many more flowers in the whorl. Both smell pretty dire.

Black Horehound is renown for its highly disagreeable pungent smell when crushed, but some folk actually like this aroma. So far, your author has been unsuccessful at finding the chemical compound(s) responsible for this foetid smell, but several candidates follow.

DITERPENOID LACTONES of the LABDANE TYPE

Black Horehound contains half a dozen Diterpenoid lactones of the Labdane type, compare Larixol. Most have an additional Furan ring (top right), or two in the case of Preleosibirin. All are loosely based on Marrubiin.


Marrubiin is also found in White Horehound (Marrubium vulgare), a related species. It is this species which used to be used in cough candy as an expectorant, although nowadays perhaps less toxic alternatives are used, i.e. purer ingredients rather than incorporating the essential oil from the whole plant(?).


One reference quotes Black Horehound as not possessing Ballonigrin (despite the name) and instead says it is present in several other Ballota species instead, but not Ballota nigra.


Preleosibirin is a Prefuranoid with, unlike the above, two acetyl groups (lower left) and two five-membered rings (upper right). It can easily be envisaged that the carbon chain linking the six-membered rings to the five-membered ring of the other five comes about as a result of the breaking of the oxygen bridge bond on the first five-membered ring (TetraHydroFuran, but your Author cannot be sure.

FLAVONOIDS

Black Horehound also contains the flavonoid Luteolin-7-O-Lactate and its glycopyranoside as well as a poly-methoxylated flavone called Tangeritin, which is present in the peel of Tangerines and other citrus fruits. Tangeritin strengthens the cell walls and also has a cholesterol-lowering effect in the human body, and may also be useful against Parkinson's Disease. It will selectively induce apoptosis in Leukaemic cancer cells whilst ignoring normal cells and has great potential for use against cancer, although it counteracts the laboratory-synthesized anti-cancer drug Tamoxifen which is already utilised medicinally to suppress the activity of natural killer cells.

The flavonoids showed some anti-fungal activity against Candida species.

PHENYL PROPANOIDS and their GLYCOSIDES

These glycosides are all based upon the non-glycoside (+)-(E)-Caffeoyl-(L)-Malic Acid, which is also present in Black Horehound.


Black Horehound also contains the following PhenylPropanoid Glycosides within the flowers: Verbascoside, Arenarioside, Forsythoside B, Ballotetroside, Alyssonoside, Lavandulifolioside and Angoroside A. These compounds are responsible for the neurosedative activity of Back Horehound, which prolongs sleep. They are able to bind to dopaminergic, benzodiazepine and morphinic receptors. The two glycosidic units present in Verbascoside and all the other Phenylpropanoid Glycosides shown here are glucopyranose and mannopyranose.


Some of these compounds demonstrated anti-fungal activity, with Arenarioside being effective against methicillin-resistant staphylococcus (MRSA). The first one, Verbascoside, has but two glycosidic units, the next five have three glycosidic units, whilst the last, Balletetroside, has four.

Pinene and Humulene have also been found in the volatile oil from Black Horehound.


  Ballota nigra  ⇐ Global Aspect ⇒ Lamiaceae  

Distribution
family8Mint family8Dead-Nettle  family8Labiatea  family8Lamiaceae

 BSBI maps
genus8ballota
Ballota
(Black-Horehounds)

BLACK HOREHOUND

Ballota nigra

Mint / Dead-Nettle Family [Lamiaceae]  

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