Definition of fire grass in US English:

fire grass

noun

  • 1English regional parsley piert, Aphanes arvensis.

  • 2North American any of various grasses that spring up on burnt land, especially Agrostis hyemalis.

  • 3A flame-coloured grass, especially one of the genus Schizachyrium.

Origin

Early 17th century; earliest use found in Gervase Markham (?1568–1637), author.