Alismatidae

Alismatidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used ; 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. 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. It consists of :

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.

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 order Alismatales, in the clade 'monocots', although the plants in Cronquist's order Triuridales are assigned to quite different placements.