Order Alismatales contains the alismatids, a group of monocotyledons (Class Liliopsida). At one point the alismatids were assigned to various distinct orders, but this approach produced polyphyletic groups, and so the whole group of families is now placed into a single order. These plants are commonly found in aquatic environmments. The families include:
Family Alismataceae
Family Limnocharitaceae
Family Butomaceae
Family Hydrocharitaceae
Family Najadaceae
Family Aponogetonaceae
Family Scheuchzeriaceae
Family Ruppiaceae
Family Cymodoceraceae
Family Posidoniaceae
Family Potamogetonaceae
Family Zannicelliaceae
Family Zosteraceae
Eelgrass Zostera marina
Family Juncanginaceae
The Triuridaceae and Petrosaviaceae have been placed here, but there actual affinities are not so clear. The alismatids as are the sister group of the Arales and the latter have sometimes been included here.
