The sweet basil plant probably originated in Asia and Africa and may have been brought to Europe in ancient times by Alexander the Great. Early settlers carried the plant and its seeds to America in the 1600s. Common basil grows throughout the U.S. as a bushy annual plant that reaches a height of 1 to 2 feet, although there are varieties with different habits. The plant has large, shiny green leaves and produces floral spikes covered with tiny white flowers. The powerful aroma of the basil plant is produced by volatile oils found throughout its stems and leaves.