The Nemesia genus contains more than 50 species, most of which are native to South Africa, but only a few are popular garden plants with various named cultivars. The two most popular species are N. strumosa and N. caerulea. N. strumosa is a true annual that produces 1-inch blue or white flowers and grows up to 1 foot tall, while N. caerulea is a more tender perennial that produces 1/2-inch blossoms in purple, pink, blue, and white on plants that grow up to 2 feet. Bu even more common as garden plants are the hybrid forms derived by crossing various Nemesia species. Nemesia plants feature lance-shaped leaves that appear in pairs along the stems, and the flowers bear a similarity to snapdragons, with a two-lipped, tubular shape. As long as temperatures remain mild, the plant can produce so many flowers that they almost entirely obscure the foliage from spring into fall.