The Indian Household Medical Guide by J. I. Lighthall (1883) has this on Poplar: This is a very valuable remeby, and should be used more than it is, and would be if everybody knew of its properties. It is a plant common to this country, and is best gathered in the fall of the year, and is within the reach of everybody.
Medicinal properties and uses.- There are two kinds of bark, white and yellow; one is as good as the other. It is very valuabel in all stomach troubles. It is a fine tonic, and should be used in cases of general debility with feeble digestion. It is good for convalescents when the appetite is deficient... I recommended equal parts of the inner barks of poplar and dogwood and sarsaparilla root, cut up fine and put in a quart bottle until it was half full, then add whisky till full, and take a large tablespoonful, or a common swallow, before each meal... I will give you an Indian formula still better than the above:
Rattle Root one part
Prickly Ash Bark two parts
Poplar Bark two parts
Sarsaparilla Root two parts
Dogwood and Wild Cherry one part
...this will cure rheumatism, give an appetite, strengthen the nerves, and purify your blood.
The images here are fresh cross-sections of an old poplar board. Notice the green color of the heartwood.
People often don't realize that Poplar is a local tree, because Aspen (another common name) is associated with the western forests (like in the Rocky Mountains).
Poplar was once a popular remedy. Today it is mostly known for its resinous buds, which are medicinal in of themselves and are the source of propolis (the sticky resin is gathered by bees). The bark has been largely forgotten as an herbal medicine. Poplar belongs to Salicaceae (the Willow Family) and contains constituents like Willow...
The Energetics of Western Herbs by Peter Holmes lists Poplar in the class of herbs that "Tonifies Urinary Qi and Harmonizes Urination"; as a "mild remedy with minimal chronic toxicity" and the energetics as "a bit bitter, astringent, cool, dry, restoring, astringing, stabalizing"; and is described for urination disorders and disorders treated by tonifying stomach qi.
Nathaniel Whitmore, herbalist