Vervain (Verbena officinalis) seems to be something of a paradoxical plant. It can grow to well over two feet tall, it has a sturdy branched stem and whilst not big leaves they are certainly in keeping with the overall stature of the plant and yet on the flowers are really small. The plant has flower spikes on several stems, often two or three inches long, and yet each one will have just two or three small flowers open at any time. A plant this size should several big bold flowers and that is not what you get. The tiny flowers are a pale mauve, possibly lilac is good description, and each flower has five small petals. Surprisingly, although few in number and insignificant in size they stand quite clearly against the drab, dark green of he stems and leaves.
In my experience vervain is not common in Dorset. It likes dry, bare patches amongst otherwise grassy places and has a preference for lime-based soils. It is more common across south eastern England than it is here further west.
Vervain is the sole British member of the verbena family. It has long held associations with healing and has spiritual connections. It was known as the holy herb and legend has it that it was used to treat the wounds of Jesus after he was removed from the cross. The small sparse flowers were said to be the tears of Mary. The plant has been used in herbal medicines for the treatment of infections in wounds.Vervain: the holy herb