The word "poke" is from the Algonquian Indian word "pakon" or "puccoon," which refers to a dye plant used for staining.
The Mohegan Indians mashed pokeberries into a poultice to relieve breast pain. The Delaware Indians used poke root teas and poultices to relieve joint pain.
Long ago, American colonists used pokeberries for ink. It's a rich purple color when fresh, but eventually it fades to tan. Thomas Jefferson wrote the Declaration of Independence with pokeberry ink. Even after all this time, the text is still legible.
During the US Civil War, soldiers wrote letters using a bird feather and pokeberry juice. These letters, too, are still legible.
During the early part of the nineteenth century, American doctors used pokeroot as a topical treatment for cancer, applied to areas of the skin where cancer was visible.
Poke is sometimes spelled "polk". Supporters of President James Polk, wore pokeweed twigs during their candidate's election campaign. They thought (mistakenly) that the plant was named for him.
After the Civil War, pokeroot was often used internally for arthritis and skin conditions. Pokeroot was believed to relieve constipation, and it was used to induce vomiting to treat certain kinds of poisoning. In the 1890s, Dr. W. W. Baxter even made one of the first "diet pills" from pokeberries.
NOTE: This photo is of pokeweed when it's beginning to make berries, which would be in late summer. The plant is too mature to eat - you should only eat poke in early spring.