Cat grass is any grass that is grown specifically for cats, usually indoors. It may be grown in a dish from which the cat chews the grass directly,[1] or just added to cat food. The most common stated benefit is to aid the passing of hairballs. Although cats may display exuberant behaviour when confronted with the grass, it has no pharmaceutical influence (contrast catnip).
The most common species sold for this purpose is a kind of oatgrass (Arrhenatherum elatius).[2] Other suitable species often mentioned are barleygrass (Hordeum vulgare), wheatgrass (Triticum aestivum), intermediate wheatgrass (Thinopyrum intermedium), ryegrass (Lolium perenne), and occasionally orchard grass (Dactylis glomerata).[3]