Magnoliopsida

Magnoliopsida is the botanical name for a class: this name is formed by replacing the termination -aceae in the name Magnoliaceae by the termination -opsida (Art 16 of the ICBN). The class will necessarily include the family Magnoliaceae, but it is not otherwise fixed. The circumscription of this class will vary with the taxonomic system that is being used.

Magnolia flowers

Cronquist and Takhtajan systems

In the Takhtajan system and the Cronquist system the name is used for the group known as dicotyledons.

Magnoliopsida in the Takhtajan system

The Takhtajan system used this internal taxonomy:
* class Magnoliopsida [= dicotyledons]
*: subclass Magnoliidae
*: subclass Nymphaeidae
*: subclass Nelumbonidae
*: subclass Ranunculidae
*: subclass Caryophyllidae
*: subclass Hamamelididae
*: subclass Dilleniidae
*: subclass Rosidae
*: subclass Cornidae
*: subclass Asteridae
*: subclass Lamiidae

Magnoliopsida in the Cronquist system

The Cronquist system used this internal taxonomy (in the 1981 version):
* class Magnoliopsida [= dicotyledons]
*: subclass Magnoliidae
*: subclass Hamamelidae
*: subclass Caryophyllidae
*: subclass Dilleniidae
*: subclass Rosidae
*: subclass Asteridae

Dahlgren and Thorne systems

The Dahlgren system and the Thorne system (1992) use the name Magnoliopsida for the flowering plants (angiosperms). However, the Cronquist system has been very popular and there have been many versions of the system published. In some of these Cronquist-based systems the name Magnoliopsida (at the rank of class) refers to the flowering plants (the angiosperms).
* class Magnoliopsida [= angiosperms]
*: subclass Magnoliidae [= dicotyledons]
*: subclass Liliidae [= monocotyledons]

Reveal system

The Reveal system uses the name Magnoliopsida for a group of the primitive dicotyledons, corresponding to about half of the plants in the magnoliids:
* class 1. Magnoliopsida
*: superorder 1. Magnolianae
*: superorder 2. Lauranae

APG systems

In the APG and APG II systems botanical names are used only at the rank of order and below. Above the rank of order, these systems use their own names, such as angiosperms, eudicots, monocots, rosids, etc. These names refer to clades (unranked). This class Magnoliopsida is not defined. Note that the idea that dicotyledons could be a taxonomic unit and get a formal name is rejected by the APG: the dicots are paraphyletic.