Hemp has been cultivated in the United States since colonial times. The fibers of the central stem are quite strong; they have been used in making rope, paper, clothing, and other products. The foliage, flowers, and seeds of female plants contain chemicals with medicinal and recreational properties. However, since World War II, it has been illegal in Illinois and other areas of the United States to cultivate hemp. The industrial form of this plant is Cannabis sativa sativa (Hemp), while the medicinal and recreational form is Cannabis sativa indica (Marijuana). It is usually the industrial form of this plant that is encountered in the wild; it has a more robust habit of growth and contains lower levels of chemicals with medicinal and recreational properties. Hemp has a unique appearance and is easy to distinguish from other species of plants. A small specimen of Hemp superficially resembles some Potentilla spp. (Cinquefoils), especially Potentilla recta (Sulfur Cinquefoil), because of the similarity of their palmate leaves. However, the leaflets of Hemp are more elongated and tapered at their tips than Sulfur Cinquefoil. Furthermore, the flowers of Cinquefoils have 5 conspicuous petals that are white or yellow, like many other members of the Rose family, while the flowers of Hemp are devoid of petals.