MOTHERWORT

Leonurus cardiaca

Mint / Dead-Nettle Family [Lamiaceae]

month8jun month8june month8jul month8july month8aug month8sep month8sept

status
statusZneophyte
 
flower
flower8pink
 
flower
flower8lilac
 
inner
inner8red
 
morph
morph8zygo
 
petals
petalsZ4
(2)
type
typeZspiked
 
stem
stem8square
 
stem
stem8fluted
 
toxicity
toxicityZmedium
 
sex
sexZbisexual
 

6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
A cylindrical spike of small pink flowers, some of which are hidden by a mass of short white hairs. Many of the lower flowers have already dropped off as they go to seed. When it grows taller, the individual whorls of flowers grow apart and short sections of the stem, hidden at the moment, become visible.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The flowers have a pink upper hood. The lower lip is not plain to see, but it has 3 lobes. So, you might say that this zygomorphic flower has 2 petals or you might say it has 1 + 3 = 4 petals. Take your pick.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The pink snake-like long forked projection from the opening of the flowers are the styles with their two stigmas.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The flowers also have 4 stamens, in two pairs: the longer pair are shaped as if to clasp something (like a pair of snipe-nosed pliers). The circles with crosses are the 4 compartments of the 4 fruits; the flowers now gone. The upper lip is densely hairy on top and like a very untidy judges wig or Boris's hairstyle!


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
A new sapling with broad leaves having many-lobes with smaller teeth.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
These leaves are quite different to the leaves in the inflorescence.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The leaves are very distinctive: in opposite pairs which are alternately at right-angles to each other all the way up the cylindrical spike of inflorescence. The leaves are also a similar length becoming only slightly shorter as they reach the summit of the inflorescent spike. The upper leaves are untoothed and lanceolate or with only 3 less-deep teeth.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The stems of the leaves are flat but incurved for stiffness. They have a slight taper from leaf to inflorescence.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The lower leaves have more deep teeth, sometimes 3, sometimes 5 whereas the upper leaves are untoothed and lanceolate or with only 3 less-deep teeth. The more teeth they have, the broader is the leaf.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The stem is square with very short hairs all along the 4 corners.


6th Aug 2019, wild in garden, Forest of Dean, Gloucestershire Photo: © Jules de Bharra
The leaves are rigid, bullate (having raised 'blisters' on the upper surface) and shiny. There are also very short hairs appressed to the upper surface of the leaves.


Uniquely identifiable characteristics

Distinguishing Feature : Just look at those stiff, lanceolate, bullate, shiny, flat-stalked leaves in opposite pairs, with alternate pairs at right-angles to each other within the inflorescence.

Some similarities to : Gipsywort (Lycopus eurapaeus) which has a similar arrangement of leaves with whorls of flowers just above them, but the whorls of flowers in Gipsywort are smaller in circumference and their leaves join the main stem directly without a long stalk and they have more teeth and are smaller.

Not to be confused semantically with : Mugwort (Artemisia vulgaris), Madwort (Asperugo procumbens), Masterwort (Imperatoria ostruthium) or Milkwort (Polygala vulgaris ssp. collina) [plants with similar names belonging to differing families].

The photographer, Jules de Bharra, adds that "the plant first appeared after we'd been in The Old Mill around 5 years. I saw it from my sitting room window growing in a rough bit of garden near the house wall. I found it in my wild flower book where it is said to be relatively rare. I've given plants and seeds away to friends and family so it can spread into the wild eventually".

Motherwort is a herbaceous perennial growing to 1.2m and spreading by rhizomes. It has sort hairs but the pink corolla is densely and untidily white-hairy on the top of the upper lip. It is a neophyte which has been naturalised in waysides and waste places, but only sparsely and becoming more scarce. It occurs over much of the British Isles, Isle of Man and the Channel Islands but is absent from Ireland.

The second binomial name, cardiaca, alludes to its former medical usage.

SECONDARY METABOLITES WITHIN MOTHERWORT

Found within the plant are the alkaloids Leonurine (aka Leonurin) and Stachydrine, plus iridoid glycoside(s) Leonuride and Leonurinidine (which look identical to your Author, but it is possible that they are stereoisomers of each other...). A diterpenoid Leocardin is also found. Many other secondary metabolites are also produced.


Leonuride, also known as Ajugol because it is also found in some species of Ajuga, is an Iridoid Glycoside, and like all those, is toxic.



Leonurin aka Leonurine is a pseudoalkaloid which has mild psychoactive properties. It is also found in plants belonging to the similar sounding Leonotis genus (which have no presence in the UK) and other plants in the Lamiaceae (mint / dead-nettle) family.



Motherwort also contains Marrubiin (aka Marrubin), as do many other plants in the Lamiaceae family. Marrubin has a similar skeleton to Leocardin. Marrubiin is also the bitter constituent of White Horehound (Marrubium vulgare) which is native and is a rarish [RR] (and getting rarer) found sparsely scattered around the UK. Marrubiin is still used medicinally to treat bronchitis or similar.
Leocardin is a diterpenoid labdane found in the aerial parts (above ground) and is present as a mixture of two C-15 epimers. As its name implies, it acts on the heart, but your Author has not been able to find out on the internet whether it acts for the benefit of the heart or is (probably) detrimental to the heart. If the latter, then, like some other compounds that are usually detrimental to the workings of the heart found in Foxglove, it may offer some benefits as treatment for some heart conditions (but that is just a guess by your Author which may be totally wrong!). All the literature on this compound is written in some foreign language which your Author cannot read nor understand.


  Leonurus cardiaca  ⇐ Global Aspect ⇒ Lamiaceae  

Distribution
 family8Mint / Dead-Nettle family8Lamiaceae
 BSBI maps
genus8Leonurus
Leonurus
(Motherwort)

MOTHERWORT

Leonurus cardiaca

Mint / Dead-Nettle Family [Lamiaceae]