Achillea millefolium, commonly known as yarrow, is a flowering plant in the family Asteraceae. It is native to temperate regions of the Northern Hemisphere in Asia, Europe, and North America. It has been introduced as a feed for livestock in places like New Zealand and Australia, where it is a common herb of both wet and dry areas, such as roadsides, meadows, fields and coastal places. In New Mexico and southern Colorado, it is called plumajillo (Spanish for ‘little feather’) from its leaf shape and texture. In antiquity, yarrow was known as herbal militaris, for its use in stanching the flow of blood from wounds. Its essential oil contains chemicals called proazulenes. The dark blue essential oil kills the larvae of the mosquito Aedes albopictus. It has seen historical use as in traditional medicine, often because of its astringent effects. It contains isovaleric acidsalicylic acidasparaginesterols, and flavonoids. The flowers and leaves are used in making some liquors and bitters. Yarrow is toxic to dogs, cats, and horses, causing increased urination, vomiting, diarrhoea and dermatitis. Credit: Wikipedia.