Cimicifuga racemosa

This photo is of Cimicifuga racemosa 'Brunette', but it is just a select form with dark leaves and looks otherwise like the green wild form. Other names by which this is called are Black Snakeroot, Black Cohosh, Bugbane, Rattle Root, Rattle Weed, Squaw Root, Macrotys, Papose Root and Rattlesnake Root. Quite a collection of names. A lot of them are also used for other plants, so I can imagine there could have been some confusion. My best guess is that these were regional names and, in a time when people traveled very little, anyone living in an area would know exactly what plant you were talking about.
This is an American native which was introduced to Europe for medicinal and ornamental purposes. It has 3 to 4 foot stalks of flowers, lovely, feathery and wandlike. The species grows over most of the eastern and middle United States, being at home in rich, open woods, which is where it is happiest here. At the end of its growing season, the rhizomes and roots are dug, dried and later powdered for medicinal purposes. An official drug for nearly a hundred years, it may be given as an extract, tincture or infusion.
Youngken's Textbook says "Cimicifuga is employed as an antirheumatic and as a remedy for chorea, dysmennorrhoea, neuralgia, and tinnitus aurium". Other writers include its use in various spasmodic affections, epilepsy, and as an astringent, diuretic, and alterative.
Potter's Cyclopaedia for instance, says, "In small doses useful in children's diahhroea. In paroxysms of consumption it gives relief by allaying the cough, reducing rapidity of pulse, and inducing perspiration ... In whooping cough its action is highly spoken of ... Said to be a specific in Saint Vitus's dance of children." Overdoses produce nausea and vomiting. A translation of the Lain genus name Cimicifuga - cim, meaning bugs and fugo, meaning drive away = suggests that the plant may be effective as an insecticide. Although it has been reputed to ward off insects, as well as cure snakebite and beesting, there are no confirming statistics to prove out these claims. I can say that it is never bothered by insects in my garden and also has never, at least so far, been munched by deer. It is a lovely plant, quite hardy, carefree and long lived. Quite highly recommended for the shade garden.
Jane