Order Gentianales is a taxonomic order of flowering plants that includes several families, including Gentianaceae, Rubiaceae, and Apocynaceae. Synonyms for this order include Gentianidae, Exaceae, and Loganiaceae. The order is characterized by the presence of opposite leaves, often with a bitter taste, and usually with distinctive tubular flowers. Gentianales species are found all over the world, from the tropics to the temperate zones, and many are important as ornamental plants or as sources of medicinal or commercial products. Despite the various synonyms for the order, it is generally recognized as an important group of plants with many ecological, biological, and agricultural applications.