Named for its effect on cats, catnip contains nepetalactone, which binds to the olfactory receptors of cats, typically resulting in temporary euphoria. It typically affects about 50% of all cats. The herbaceous perennial plant is native to Europe, Asia and Africa, and has increasingly become common in North America. It grows to a size of about 1 metre by 1 metre, with sturdy stems with opposite heart-shaped, green to grayish-green leaves. Its flowers are small and white or lilac, growing in clusters, and its stems have the characteristic squareness of plants in the mint family. Catnip has a history of human medicinal use for its soothing properties. It has also been known to have a slightly numbing effect. The plant has been consumed as a tea, juice, tincture, infusion or poultice, and has also been smoked.