Alismatidae

Alismatidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used (there are many such systems); the only requirement being that it includes the family Alismataceae. It is a relatively new name: earlier systems, such as the Engler and Wettstein systems, used the name Helobiae for a comparable unit.

Alismatidae in the Takhtajan system
The Takhtajan system treats this as one of six subclasses within the class Liliopsida (=monocotyledons). It consists of:


 * subclass Alismatidae
 * superorder Alismatanae
 * order Butomales
 * order Hydrocharitales
 * order Najadales
 * order Alismatales
 * order Aponogetonales
 * order Juncaginales
 * order Potamogetonales
 * order Posidoniales
 * order Cymodoceales
 * order Zosterales

Alismatidae in the Cronquist system
The Cronquist system treats this as one of four subclasses within the class Liliopsida (=monocotyledons). It consists of (1981):


 * subclass Alismatidae
 * order Alismatales
 * order Hydrocharitales
 * order Najadales
 * order Triuridales

This subclass comprises less than five hundred species total: many of these are aquatic or semiaquatic plants (see Alismatidae info).

APG II system
The APG II system does not use formal botanical names above the rank of order; it assigns most of the plants involved to the (expanded) order Alismatales, in the clade 'monocots', although the plants in Cronquist's order Triuridales are assigned to quite different placements.