Jersey knapweed, scientifically known as Centaurea nigra, is a perennial flowering plant that is commonly found in Europe and Asia. It is also known by other names such as black kecks, lesser kecks, hardheads, and horse-button. The name "knapweed" comes from the German "knappen" meaning to break or snap and refers to the tough stem of the plant. The plant has been used for medicinal purposes, including for treating headaches and as a diuretic. It is also considered a valuable source of food for bees and other insects. However, due to its invasive nature, it is sometimes considered a weed and can be potentially harmful to other plant species.