This popular ornamental species is from South America. The less decorative common European Vervain, Verbena officinalis was considered by the Greeks, the Romans and the Celts to be sacred and they used it to cleanse the altars within their temples. It was also used medicinally for a variety of ailments including pains in the womb, and relief during confinement. Since antiquity it has been dedicated to the goddess Venus. This resulted in its use as a love potion throughout Europe until just before the 1950's.
There is evidence to suggest that it was being given to young newly-weds right up until that time by those with a sense of mischief. It is steeped in magic and folk-lore and was very much seen as a plant which would bring protection from evil and death.