||There are about 370 species of annual, perennial and shrubby plants in this genus, which is found throughout the world in both temperate and tropical climates. This wide distribution is reflected in diverse growth habits, ranging from low spreading herbs to tall and almost tree-like species. They are grown for their attractive tubular flowers which have split or flaring petals and range in color through all the bluish tones, from white to pink and purple, as well as scarlet and yellow-red combinations.
||CULTIVATION: Cultural requirements vary due to the wide range of natural habitats in which the species are found. The commonly grown species are happy in any reasonably fertile well-drained soil in sun or part-shade, with some preferring a moister situation. The shrubbier species generally need a warm well-drained situation; although they require adequate moisture, a wet site will cause them to rot. In cool-temperate climates most will require greenhouse cultivation. Propagation is usually from seed sown in spring or from division.