Hierochloe odorata or Anthoxanthum nitens, also known as Sweet grass, Holy grass (UK), Bison grass (Poland), Manna grass, Mary' grass, Peace grass, Vanilla grass or Unity grass, is an aromatic herb native to northern Eurasia and North America. It is used in herbal medicine and in the production of distilled beverages (e. g. , Zubrówka, Wisent). It owes its distinctive sweet scent to the presence of coumarin. In North America Hierochloe odorata occurs in southern Canada, northern Great Plains/Rocky Mountains and northwest of U. S. , and New England. In continental Europe it occurs north from Switzerland. There is only one site in Ireland, and it is recorded in four counties of Scotland. Uses. The plant is harvested by cutting grass in early to late summer at the desired length. Hierochloe odorata harvested after the first frost has little or no scent and is less desirable for basketry. Basketweavers sun-dry cut sweet grass until it is dry and brittle. The brittle form of sweet grass must be soaked in warm water until it becomes pliable. The pliable grass is typically braided into thick threads and then redried for use. European traditions.