Mary Gold, the Trifid Bur, Trifid Double-tooth, Water-hemP, or Hemp-agrimony ; Bi-dens triparlita, L. an indigenous annual plant, growing in marshy and watery places, and flowering in the months of August and September.—Dambourney and other writers inform us, that both the fresh and dried herb imparts to wool, with the addition of alum, a very bright yellow colour : the yarn or cloth, however, should be washed and dried before it is immersed in the dyeing liquor, in which it ought to be boiled for two hours; and, in order to extract more effectually the colouring particles, the plant must be cut in small pieces, put in the vessel, in alternate layers with the substances to be tinged, and properly agitated.

There is another species, namely, the Bidens cernua, or Nodding Marygold, which is possessed of similar properties.