Achillea millefolium - YARROW
Species: A. millefolium
Achillea millefolium, commonly known as yarrow /ˈjæroʊ/ or common 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 live stock in places like New Zealand and Australia. However, it is a weed in those places and sometimes also in its native regions.
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. Other common names for this species include gordaldo, nosebleed plant, old man's pepper, devil's nettle, sanguinary, milfoil, soldier's woundwort, thousand-leaf, and thousand-seal.
A. millefolium is an erect, herbaceous, perennial plant that produces one to several stems 0.2–1 m (0.66–3.28 ft) in height, and has a spreading rhizomatous growth form. Leaves are evenly distributed along the stem, with the leaves near the middle and bottom of the stem being the largest. The leaves have varying degrees of hairiness (pubescence). The leaves are 5–20 cm (2.0–7.9 in) long, bipinnate or tripinnate, almost feathery, and arranged spirally on the stems. The leaves are cauline, and more or less clasping.
The inflorescence has 4 to 9 phyllaries and contains ray and disk flowers which are white to pink. The generally 3 to 8 ray flowers are ovate to round. Disk flowers range from 15 to 40. The inflorescence is produced in a flat-topped capitulum cluster and the inflorescences are visited by many insects, featuring a generalized pollination system. The small achene-like fruits are called cypsela.
The plant has a strong, sweet scent, similar to that of chrysanthemums.
Yarrow grows from sea level to 3,500 metres (11,500 ft) in elevation. The plant commonly flowers from May through June. Common yarrow is frequently found in the mildly disturbed soil of grasslands and open forests. Active growth occurs in the spring.
In North America, both native and introduced genotypes, and both diploid and polyploid plants are found. It is found in every habitat throughout California except the Colorado and Mojave Deserts. Common yarrow produces an average yield of 43,000 plants per acre, with a total dry weight of 10,500 lbs.
The plant is found in Australia as an introduction.
Yarrow is considered an especially useful companion plant, repelling some pest insects while attracting good, predatory ones. It attracts predatory wasps, which drink the nectar and then use insect pests as food for their larvae. Similarly, it attracts ladybirds and hoverflies.
A. millefolium can be planted to combat soil erosion due to the plant's resistance to drought. Before the arrival of monocultures of ryegrass, both grass leys and permanent pasture always contained A. millefolium at a rate of about 0.3 kg/ha. At least one of the reasons for its inclusion in grass mixtures was its deep roots, with leaves rich in minerals. Thus its inclusion helped to prevent mineral deficiencies in the ruminants to which it was fed.
It was introduced into New Zealand as a drought-tolerant pasture. It is very prevalent.
Yarrow has also been used as a food or in teas, and was very popular as a vegetable in the 17th century. The younger leaves are said to be a pleasant leaf vegetable when cooked like spinach, or in a soup. Yarrow is sweet with a slight bitter taste. The leaves can also be dried and used as an herb in cooking.
In the Middle Ages, yarrow was part of an herbal mixture known as gruit used in the flavoring of beer prior to the use of hops. The flowers and leaves are used in making some liquors and bitters.