{{Short description, Subclass of flowering plants Alismatidae is a

botanical name A botanical name is a formal scientific name conforming to the ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) and, if it concerns a plant cultigen, the additional cultivar or cultivar group, Group epithets must conform t ...

at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used (there are many such

systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and is exp ...

); the only requirement being that it includes the family

Alismataceae The water-plantains (Alismataceae) are a family of flowering plants, comprising 20 genera (17 extant and 3 fossil) and 119 species. The family has a cosmopolitan distribution, with the greatest number of species in temperate regions of the Northe ...

. 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 A list of systems of plant taxonomy, system of plant taxonomy, the Takhtajan system of plant classification was published by Armen Takhtajan, in several versions from the 1950s onwards. It is usually compared to the Cronquist system. It admits Para ...

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 The Cronquist system is a list of systems of plant taxonomy, taxonomic classification system of angiosperms, flowering plants. It was developed by Arthur Cronquist in a series of monographs and texts, including ''The Evolution and Classification of ...

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 In biology, being semi-aquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water (in ...

plants (se
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 Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are flowering plants whose seeds contain only one embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but with various ranks a ...

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