Phleum is a genus of annual and perennial grasses in the family Poaceae (order Poales), commonly known as timothy or cat's-tail grasses. Described by Linnaeus in his Species Plantarum (1753), the genus encompasses around 15–17 accepted species, with the GBIF backbone recognising up to 36 total taxa including varieties and subspecies.
Plants in the genus are tufted grasses, typically lacking stolons or rhizomes, and grow 20–150 cm tall. They are characterised by their striking cylindrical, spike-like panicles packed with dense spikelets. The glumes are typically keeled and may bear short awns. Leaves are flat, rolled rather than folded, and often hairless.
The genus is native to Europe, Asia, and north Africa. One species, Phleum alpinum (alpine timothy), extends its range into both North and South America. The most economically significant member, Phleum pratense (common timothy), has been widely naturalised across North America, eastern Asia, southern South America, and Australasia following its deliberate introduction as a forage grass.
Several species are important for cattle feed and as hay for horses and other domestic animals. Timothy hay — from P. pratense — is also a widely used staple food for domestic rabbits, guinea pigs, chinchillas, and degus, prized for its long fibre content and abrasive texture that helps maintain healthy teeth. Timothy grass pollen is also used medicinally in allergen immunotherapy for hay fever treatment.
Etymology
The genus name Phleum is a Latinised form used by Linnaeus (1753), derived from a classical Greek name for a reed-like grass. The familiar common name "timothy" honours Timothy Hanson, a British farmer who promoted P. pratense as a hay crop around 1720; before that association, the plant was called "hurd grass" after John Hurd, who first described it in 1711 from plants growing in New Hampshire.
Distribution
The genus is native to Europe, Asia, and north Africa, with the alpine species Phleum alpinum also occurring naturally in North and South America. Phleum pratense has been widely naturalised beyond its native Eurasian range and is now established throughout most of North America, eastern Asia, southern South America, and Australasia following intentional introduction as a forage grass.
Ecology
Timothy grasses typically colonise meadows, roadsides, abandoned fields, and grasslands, generally favouring nutrient-rich, moist soils, though P. pratense can grow on a range of soil types from sandy to heavy clay at pH 4.5–7.8. The genus is adapted to cool, humid, temperate climates. Several lepidopteran larvae use timothy as a food plant, including the Essex skipper (Thymelicus lineola) and the marbled white (Melanargia galathea). The genus flowers in summer (June–August for P. pratense), with wind pollination.
Cultivation
Phleum pratense is widely cultivated as a forage grass for cattle and, especially, as hay for horses. It is best suited to cool, humid, temperate regions on heavy, deep, moist soils, and tolerates a wide range of annual precipitation (35–176 cm) and pH (4.5–7.8). It is not drought tolerant and yields less on light dry soils. The plant yields up to 15 tonnes of plant material per hectare. Several named cultivars have been developed for improved yield, disease resistance, and nutritional value. Timothy hay is a commercially important product for the small-animal pet trade, used as a dietary staple for rabbits, guinea pigs, and chinchillas.
Propagation
Phleum pratense is propagated by seed sown in spring in situ, barely covered. When seed is limited it can be surface-sown in a pot in a cold frame, pricking out seedlings when large enough and planting out in summer. Division in spring is also an option for established clumps.
