Distinguishing Feature : a rather straggly bush-like plant with stiff square stems, and a spike of 5-petalled pale-lilac flowers held closely to the stem on short stalks. Has very few branches, those it does have emerge in pairs at 45 degrees upwards near the top of the stem.
Although there are hundreds of garden plants in the Verbena family, Vervain is the only one that makes an appearance in any Wild Flower book. Vervain is a native plant of India and there it has long been associated with traditional treatments as a relaxant, nerve tonic, galactogogue, diaphoretic, anti-spasmodic and hepatic. The Chinese use Vervain for migraine and controlling female sex hormone fluctuations. Many of the compounds found in Vervain shown below are thought to be responsible for these actions.
In many parts of Europe the methanol extracts of aerial parts of Vervain (which contain Verbenalin, Hastatoside, Verbascoside and β-Sitosterol-D-glucoside) are used to treat the early stages of fevers, colds and nervous disorders as well as tooth decay and halitosis.
Wikipaedia lists several sub-species, but your Author knows not whether any occur in the UK. If some do, this may explain the slight differences in leaf shape near the bottom of the two specimens depicted above and the dichotomy in stem shape: square and round.
Vervain contains Verbenol, a pleasantly smelling terpene that has chemical similarities to that of Myrtenol contained within Bog Myrtle. It is valued as a food flavouring, and has also been utilised (together with Myrcene and
Exo-brevicomin [neither of which are produced within Vervain) as a pheromone attractant for male mountain beetles (if they occur in the UK). Verbenol exists in two isomeric forms, cis- and trans- verbenol which themselves can exist in differing stereo-isomeric forms, the (S) and (R) enantiomers.
A herbal tea made from Vervain has traditionally been used for the treatment of insomnia and other nervous conditions. The active principles responsible for these pharmacological effects are the glycosidic iridoids
Hastatoside, which Vervain contains. Both increased the amount of non-REM sleep after being administered to patients at night time. Both also increased the delta-wave activity in the brains during the non-REM sleep. Glc is an abbreviation for the monosaccharide
Glucose In addition, Verbenalin exhibits uterine stimulant activity and has a direct action on smooth muscles. It is used as a drug by the veterinary profession.
PHENYL PROPANOID GLYCOSIDES
Vervain also contains two glycosides of phenyl-propanoids, Verbascoside and
Eukovoside. Verbascoside , as its name suggests, was first found in Verbena. These, as well as Aucubin (aka aucuboside), are thought to possess galactogogue and emmenogogue actions.
phenylethanoid glucoside, also occurs in