Populus Tremuloides
Quaking aspen is a deciduous tree, related to poplar and birch, that grows up to 70ft. It has round, toothed, green leaves that are slightly white-ish on the underside. The name of this tree stems from the shimmering appearance of the leaves when there is a breeze.
This tree is native to North America and prefers damp or moist areas with medium to full light. It is now cultivated throughout temperate regions. It is often considered a weed tree, because if its quick growth and its tendency to take over cleared or burned areas of land.
The bark of this tree contains salicin and populin, which are salicylates. Salicylates, which are the precursor to aspirin, are fever reducing, pain relieving, and anti-inflammatory. The bark is also astringent and antiseptic and is used to treat internal illnesses such as irritable bowel syndrome and urinary tract infections.
People who are sensitive to aspirin should never take the bark as a remedy.