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
Leonurin) and Stachydrine, plus iridoid glycoside(s)
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.
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
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.