Gentianales is an order of flowering plants, included within the asterid clade of eudicots. It comprises more than 20,000 species in about 1,200 genera in 5 families.[1] More than 80% of the species in this order belong to the family Rubiaceae.
Many of these flowering plants are used in traditional medicine.[2] They have been used to treat pain, anxiety, cancers and neurological conditions.
In the classification system of Dahlgren the Gentiales were in the superorder Gentianiflorae (also called Gentiananae). The following families are included according to the APG III system:[3]
It takes its name from the family Gentianaceae, which in turn is based on the name of the type genus, Gentiana. The genus name is a tribute to Gentius, an Illyrian king.
This large order has a variety of different plants, ranging from small herbaceous plants and saprophytes to shrubs and large trees.[5] Species are, however, united by their simple and opposite leaves and typically have showy pentamerous flowers (flowers in which components occur in multiples of five) and show nuclear endosperm formation (in which cell division takes place without the cell wall forming between divisions).[1][5] Many species have structures between the leaf petioles, such as ridges or stipules.[5] Many species also have colleters; thick hair-like structures that secrete mucilage, a thick gluey substance.[5]
Species of this order are found in moist climates around the world. They are most common in tropical regions.[5]