The Collaborative International Dictionary
Madder \Mad"der\ (m[a^]d"d[~e]r), n. [OE. mader, AS. m[ae]dere; akin to Icel. ma[eth]ra.] (Bot.) A plant of the genus Rubia ( Rubia tinctorum). The root is much used in dyeing red, and formerly was used in medicine. It is cultivated in France and Holland. See Rubiaceous.
Note: Madder is sometimes used in forming pigments, as lakes, etc., which receive their names from their colors, such as madder yellow.
Field madder, an annual European weed ( Sherardia arvensis) resembling madder.
Indian madder, the East Indian Rubia cordifolia, used in the East for dyeing; -- called also munjeet.
Wild madder, Rubia peregrina of Europe; also the Galium Mollugo, a kind of bedstraw.
Wikipedia
Rubia peregrina, the common wild madder, is a herbaceous perennial plant species belonging to the bedstraw and coffee family Rubiaceae.