Willow

Willow was the original source of aspirin: the most commonly used drug in the world. Willow bark has been used in traditional medicine for up to 3500 years. It was first used by the Sumerians and Egyptians as an analgesic, and its use for pain relief continued with the Greeks, who used it for the pain of childbirth. In the 18^th century, willow bark’s efficacy in treating fevers was first discovered, and in the 19^th century its active ingredient salicin was first refined and isolated from the bark. At the end of the 19^th century a German dye manufacturer, Bayer, set up a pharmaceuticals division which resulted in the rapid development of a number of drugs, including aspirin and heroin. Over time, research into the effects of aspirin demonstrated that it had adverse gastrointestinal effects, but that it could also prevent platelet aggregation and be used to prevent strokes, cardiovascular diseases and deep vein thromboses.

Willow is also cultivated in Sweden as biomass for energy production, but it has been found that, when burnt, its ash contains up to ten times as much cadmium as forest trees. This has led researchers to explore whether it could be useful as a phytoextractor of heavy metals from contaminated soils. Willow can be planted in the contaminated soil, where it grows quickly with deep roots, all the while drawing cadmium and zinc up out of the soil in a way that doesn’t damage the soil structure. These metals can then be extracted from the harvested wood or disposed of safely, leaving behind fertile and decontaminated soil.