The US is home to 127 members of the violaceae family, in three genera (hybanthus, isodendrion, viola), of which the latter has by far the most species. In the US, plants are mostly herbs, producing attractive, colorful flowers that usually have bilateral symmetry. Leaves grow at the base and along the stems, alternately attached; they may be simple or compound, and have small stipules. Flowers are borne singly or in clusters. Flowers are formed of five sepals, separate or only slightly fused, and five petals, of which the lowest is wider and different in shape, often forming a pouch and/or a backwards-projecting spur. The five stamens have short filaments, so remain largely hidden at the flower center.