Large genus of around 586 annual and perennial plants with tuberous structures. Some species are evergreen but most are herbaceous. This genus is distributed in mountainous regions of the temperate Northern hemisphere and tropical Eastern Africa, with the most species located in China. Their foliage is often heavily divided, creating a fern-like appearance and they are also grown for their flowers, which are tubular, 2-lipped and spurred. Flowers range in colour, with blue, yellow, purple, pink and white variations commonly found and bicolour varieties with contrasting colours such as pink and yellow also present.