Polygala albida

This species is a perennial herb with multiple stems up to 50 centimeters tall. The stems are usually unbranched, but some old plants can have branching stems. A mature plant can have up to 70 stems growing from a hard, woody rootstock that spreads horizontally. The lance-shaped leaves are alternately arranged. The lower leaves are reduced and scale-like. The inflorescence is a spike of rounded white or greenish flowers. The fruit is a capsule containing two hairy black seeds. The root is twisted and conical, with a scent somewhat like wintergreen and a very pungent taste. There are two root polymorphisms; a northern morph growing in Canada and toward Minnesota has larger roots up to 15 cm long by 1.2 cm wide which are dark brown and sometimes purplish toward the top, and a southern morph found in the southeastern United States that has smaller, yellow-brown roots. The plant grows on prairies, in woods, in wet shoreline and riverbank habitat. It grows in thin, rocky, usually calcareous soils. It also occurs in disturbed habitat, such as roadsides.

This plant had many uses among Native Americans. The Cherokee used it as an expectorant and a diuretic, and for inflammation, croup, and common cold. The Chippewa used preparations of the root to treat convulsions and bleeding wounds. The Cree chewed the root for sore throat and toothache. According to Canadian botanist Frère Marie-Victorin, the Seneca may have been inspired to use the root to treat snakebite by its resemblance to the tail of a rattlesnake.

The root was exported to Europe in the 1700s and was sold widely by pharmacists into the 1800s. It was marketed as a treatment for pneumonia. It is still in use as an herbal remedy. It is ground and made into patent medicines, mainly remedies for respiratory complaints. It is added to cough syrups, teas, lozenges, and gargles. It is toxic in large amounts, and overdose causes such symptoms as diarrhea and "violent vomiting". The powdered root can be sternutatory (sneeze-inducing). The root product is called Senegae Radix, Radix Senegae, or simply senega. Active compounds include saponins such as senegin, as well as phenolic acids, sorbitol derivatives, methyl salicylate (oil of wintergreen), and sterols. The expectorant property comes from the irritation of mucous membranes by the saponins, which causes an increase in respiratory secretions and a decrease in their viscosity, giving a productive cough.