Timothy, or Herd's-grass, a grass that is grown as a hay crop. Timothy is one of the most important grasses produced for hay in the United States. The plant, which grows to about five feet (1.5 m) in height, has clusters of smooth, straight stems. Each stem bears flat leaves about 12 inches (30 cm) long and cylinder-shaped flower heads up to six inches (15 cm) long. Timothy is widely grown in the northeastern United States and southeastern Canada.

Timothy was named for Timothy Hansen (or Hanson) of Maryland. Hansen, who is said to have introduced the seed from England in 1720, and was responsible for spreading the cultivation of timothy throughout Virginia and nearby areas. The name herd's-grass is derived from John Herd, who supposedly found the grass growing wild in a New Hampshire swamp in 1700. Herd began cultivating the grass, and was responsible for its subsequent cultivation throughout New England, New York, and Ontario.

Timothy is Phleum pratense of the grass family, Gramineae.