VERVAIN

The long spikes of Vervain (Verbena officinalis) are easily overlooked because the flowers are so small.  The plant is happy in alkaline conditions such as chalky soil or old mortar.  It has long been used for medical and mystical purposes and was once thought to ward off headaches, poisonous bites and the plague.  

Although the flowers have a pink tinge, to me they sometimes look bluish.  How does that happen?

The leaves divide in a way that is called pinnatifid in botanical circles and the branches also divide.

Small but beautifully formed.