Heliotropium is a genus of more than 200 species of low, bushy, flowering shrubs, native to warm climates of the Americas. Some species of heliotropium, particularly H. arborescens, are grown in flower gardens for their sweetly scented, usually purple or violet flowers. The English name of the genus, as well its most commonly cultivated species, is heliotrope.
The heliotropium genus is native to the southern United States, central and South America, and some Pacific islands. When wild, the genus' species can be found in open, arid scrub lands. The approximately 250 members of this genus are usually shrubs or short woody plants that bear bunches of tiny, fragrant flowers. They are usually considered annuals, but may survive as short-lived perennials in climates with mild winters. Heliotropium plants have hairy leaves with a rough surface.
When cultivated for their flowers, heliotropium species are usually grown as annuals. The most commonly cultivated species is H. arborescens. Plants are short and compact, reaching about 2 feet (61 cm) at their tallest, with a 1 foot (30 cm) diameter. The very small flowers, long appreciated for their aroma, grow in rounded bunches that can be quite large. Although they are very sensitive to frost and cold weather, the plants flourish in containers and can be brought indoors during the winter.
Modern varieties of the species H. arborescens, commonly called heliotropes, include the violet "Marine," the white-flowered "White Lady," and the dwarf "Mini Marine." These varieties sometimes appear in windowboxes and on window sills, due to their tolerance for being grown in containers. Outside, they can be intermixed with other garden flowers or appear in a butterfly garden, as they attract butterflies. Like other species of the genus, H. arborescens prefers full sun and moderate watering.
Heliotropes were brought to Europe from Peru in the 18th century, where they spread across the European continent. Thomas Jefferson grew them in his garden with seeds obtained from France. The flowers were also prized by Victorian gardeners in England during the latter half of the 19th century.
The genus name reflects the fact that the plant tends to follow the path of the sun, as the Greek elements of heliotropium mean "sun" and "turning." The name cherry pie plant was applied because of the sweet scent of heliotrope flowers, which has also been likened to other sweet fruits or vanilla. Another name for the plant, turnsole, entered English from a French translation of the Greek word heliotrope.