Monday, August 20, 2012

The Achilles flower: common yarrow

Species name: Achillea millefolium

Common name: Yarrow

Location: Ontario

The common yarrow plant (the real yarrow; not the plant masquerading around as a yarrow with the common name "golden yarrow") is native to the Northern Hemisphere, with most subspecies native to North America. Since I have no idea what subspecies this is, I'll just give the plant the benefit of the doubt and say it's native. Even if it wasn't truly native, it would be close enough! Most common yarrow plants have either white or pink flowers, and yellow flowers would be considered incredibly unusual (and traditionally would only be one or two flowers in a sea of either white or pink). Since we as human beings like variety in our flower gardens, we have exploited the natural mutations in the yarrow population for yellow flowers, and created varieties and cultivars with varying shades of yellow flowers. The ones found in nature, however, are always either white or pink; if you see a yellow yarrow you know it's a garden escape. This isn't necessarily a bad thing depending on the variety or cultivar; as long as there wasn't too much "modification" that was done in the breeding process, all of the genes in the native population that were for disease resistance, etc., would still be in the cultivated population. In general, the longer a plant has been in domestication the poorer the competitor it is back in its native range. If you think about the challenges domesticated corn must have in reproducing, or whether or not a Yorkie dog would survive in the wild on its own, you can see how this generally holds up with domesticated species. Due to the shape of the florets within each inflorescence, the shape of each inflorescence appears to be a 5-petaled flower. This actually isn't the case, and this plant is in the sunflower family or the Asteraceae. Each inflorescence contains 4 to 5 ray florets (the ones that look like petals), and many disc florets.

Yarrow has a long history of being used as a medicinal plant; in fact, the Latin name Achillea refers to Achilles who apparently carried it with him into battles to treat the wounds of his soldiers (where one of the common names of this plant comes from; soldier's woundwort). It has been used as a diaphoretic (a chemical or group of chemicals that cause sweating; this was a very popular treatment for various "blood disorders" in ancient times), an astringent (would be very effective against facial acne since it has a relatively concentrated amount of salicylic acid in the leaves and roots), a tonic, and a stimulant. The essential oils from the flowers were extracted using the steam distillation process and used as an anti-inflammatory agent. Depending on the expert herbalist and the disorder, it was also used to either prevent bleeding or promote it. The Navajo also used it to relieve the pain associated with toothache. These are only a few of the reported medical uses of yarrow; for a complete list you can read about it on the Wikipedia page HERE.

A word of caution if you have yarrow in your garden or come in contact with it in the wild: there are some people who experience a violent skin reaction to contact with the leaf juices from broken yarrow leaves, and sometimes with the unbroken leaves themselves. This skin rash is photosensitive so is made worse by the sun, if skin irritation wasn't enough for you. There is also the reported effect that it can cause impotence in male mice, although no evidence has shown this effect is translated in humans. It's probably better to be safe then sorry with this plant; unless you know you don't show sensitivity to the plant, it's probably best to wear gardening gloves when handling it.

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