Fifty two genera from the plantaginaceae (plantain) family are represented in the US, of which one (penstemon) accounts for over half of the 247 species. All plants are herbs, with predominantly undivided, basal leaves, and flowers produced in clusters, elongated or branched. Most species have flowers with four sepals, fused at the base, and a two-lipped corolla, the lower lip divided into three lobes, the upper lip into two. Flowers have two or four stamens, and may have one or two staminodes (infertile stamens). The plantaginaceae family has expended in recent years with inclusion of genera from other families, such as penstemon from the scrophulariaceae.