The Collaborative International Dictionary
Orris \Or"ris\, n. [Prob. corrupted from It. ireos iris. See Iris.] (Bot.) A plant of the genus Iris ( Iris Florentina); a kind of flower-de-luce. Its rootstock has an odor resembling that of violets.
Orris pea (Med.), an issue pea made from orris root.
Orris root, the fragrant rootstock of the orris.
Wikipedia
Iris florentina is the white flowered variant of Iris germanica now classified as Iris germanica nothovar. florentina. It is cultivated as an ornamental plant in temperate regions almost worldwide. It is also grown to produce orris-root, a scented substance used in perfumes, soaps, tooth cleanser, clothes washing powder. Medicinally it was also used as an expectorant and decongestant. It is made from the rhizomes of Iris florentina, Iris germanica and Iris pallida.