Hierochloe odorata or Anthoxanthum nitens, also known as Sweet grass, Holy grass (UK), Bison grass (Poland), Manna grass, Mary’s 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., Żubrówka, Wisent). It owes its distinctive sweet scent to the presence of coumarin.
This variety of grass is different from the species commonly known as Buffalo grass (Stenotaphrum secundatum) in Australia.
Hierochloe odorata is a very hardy perennial, able to grow to the Arctic Circle. Its leaves do not have rigid stems, so only grow to about 20 cm (7.9 in) in height, and then the leaves grow outward horizontally to 100 cm (39 in) long or more, by late summer. The base of the leaf, just below the soil surface, is broad and white, without hairs; the underside of the leaf is shiny, without hairs. In the wild, the bases of the leaves are frequently purple-red colored, and this indicates a phosphorus-deficient soil.