Sunday, July 5, 2015

A Well-Known Plant: Yarrow - Achillea millefolium - Herbe à dinde

The star of the day is one of the most broadly-distributed and -recognized wildflowers around: Achillea millefolium (common yarrow, also many other names).

Achillea millefolium inflorescence
This species (actually a huge complex of subspecies) is native more or less to the northern hemisphere's temperate zones, but particular subspecies are native to more restricted areas. This helps to understand the US range map of this plant, which lists the species as both native and introduced on most of the North American continent. This is because some subspecies are native, and others are introduced (particularly from Europe). The Canadian range map is considerably less detailed, going for the simple statement that the plant is native to all parts of Canada. This plant is listed as weedy/invasive in the US [1] but does not have weed status in any of the provinces or territories where such statuses are conferred [2].

Achillea millefolium whole plant
One of the main reasons for Achillea millefolium's fame is its array of purported and variously justified medicinal uses. This plant is a very popular herbal remedy [3,4] with a very long history of use in traditional medicine [3,4,5,6,7,8] for a wide variety of ailments. Modern analyses and tests have confirmed its efficacy as an anti-inflammatory at least in vitro [9], and there is some speculation (which I mention in my previous post about this plant) that the salicylic acid in the plant may make it an effective painkiller [3]. Other claims about the plant's medicinal value are currently insufficiently assessed to make a judgement on.

Achillea millefolium inflorescence lateral view
Regardless of its particular efficacy as a medicine, I do enjoy a cup of tea with the flowers or leaves of Achillea millefolium from time to time. The flavour, though strong, is pleasantly herbal. There is evidence that prolonged use can be potentially harmful and that it is possible to suffer allergic reactions to the plant [3,4], so I do not recommend that anybody consume it too frequently.

Achillea millefolium being pollinated by flies
Achillea millefolium is a hardy, drought-resistant [3,4,5,6,8,10] perennial with an extensive root system [3,4,5,6,8] that makes it suitable for habitat restoration in areas where erosion control is needed [6]. It is an obligate outcrosser [3,6], meaning that it must be pollinated with pollen from a different individual in order to produce seed. It is pollinated by insects [3,8], including beetles, flies, syrphid flies, wasps, and bees [6].

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