Populus is a genus of trees that includes the cottonwoods, poplars, and aspens, all of which are sometimes termed poplars or popples. Most of the available scientific evidence has reported on aspen, and there are very few reports mentioning cottonwood.
Aspen is a deciduous tree native to northern hemisphere temperate climates. Although aspen has shown antibacterial and antiplatelet activity, there is currently insufficient available evidence in humans to support the use of aspen for any indication.
Aspen pollen, bark, wood, and saw dust are known to cause allergic reactions in sensitive people, including contact dermatitis, rhinoconjunctivitis, and asthma, and there may be cross-sensitivity to other tree pollens, especially in the Salicaceae family.
The U.S. Food and Drug Administration (FDA) lists poplar buds (Populus balsamifera, P. candicans Ait., and P. nigra L.) as Generally Recognized as Safe (GRAS) for flavoring.
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