Hierochloe odorata or Anthoxanthum nitens, also known as sweet grass, buffalo grass, bison grass, holy grass (UK), manna grass, Mary’s grass, seneca grass, sweetgrass, or vanilla grass, is an aromatic herb which grows in northern Eurasia and in 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.

Characteristics
Very hardy perennial. Native to North America as well as Europe. Grows to about 60 cm (24 in) in height, leaves grow 60 cm (24 in) long by late summer. Bases of leaves, just below soil surface are broad and white, without hairs, underside of leaves are shiny, without hairs.

Taxonomy
The name Hierochloe odorata is from the Greek, literally “holy fragrant grass”. Some authors include Hierochloe in Anthoxanthum; in this case this species is given the epithet nitens to avoid confusion with a different species, Anthoxanthum odoratum, sweet vernal grass.

Propagation
Easiest by cutting out plugs from established plants. Grown in sun or partial shade, they do not like drought.

Distribution
Northern America: southern Canada, northern Great Plains/Rocky Mountains and Northwest of U.S., and New England

Europe: from Switzerland north. Only one site in Ireland, and four counties in Scotland; making it very rare in the British Isles