Asteridae is a botanical name at the rank of subclass. Circumscription of the subclass has varied with the taxonomic system being used but by definition always includes the family Asteraceae (Compositae). One of the better-known and more influential systems that formally recognized subclass Asteridae was the Cronquist system devised by botanist Arthur Cronquist, which included the orders:

• Gentianales
• Solanales
• Lamiales
• Callitrichales
• Plantaginales
• Scrophulariales
• Campanulales
• Rubiales
• Dipsacales
• Calycerales
• Asterales

Most of the above orders as defined by Cronquist have been dramatically redefined on the basis of recent molecular systematic studies.

To a large extent Cronquist's subclass Asteridae corresponds with the older concepts of Sympetalae and Tubiflorae, groups that were defined by having their petals united into a tube. However, these older classifications contained some sympetalous families, such as Cucurbitaceae, that are now known not to be closely related. Cronquist's concept also corresponds closely with the APG II group of euasterids but the APG does not formally recognize a group called "Asteridae" (or any other group above the rank of order).

Recent phylogenetic studies have suggested that several families, including three major orders not included in Asteridae by Cronquist, Ericales, Cornales, and Apiales, also belong to the asterid group. The circumscription of subclass Asteridae, as well as the circumscriptions of the orders contained within it, is currently in a state of flux; many systematic botanists refer to these as clades (asterids, euasterids, etc., rather than use formal names such as subclass Asteridae.

[edit] External links

• Asteridae (Cronquist system)
• Asterids
• Phylogeny and the evolution of flower symmetry in the Asteridae
• The Phylogeny of the Asteridae sensu lato Based on Chloroplast ndhF Gene Sequences (link to abstract)
• Phylogeny of the Asteridae s. str. based on rbcL sequences, with particular reference to the Dipsacales (link to abstract)