The Water-Plantain family has around 18 genera and 90 (88 to 120) species.

The aquatic herbs are mostly perennial and grow from an underground stem in the form of a corm, stolon or rhizome.
They can float on the water or be above or in it.

The simple basal leaves, almost always on a petiole are spirally arranged.
Their bases sheath the stem.
Juvenile leaves are linear as are the submerged adult ones.
Adult leaves above the water are linear, ovate or triangular with basal lobes.
The veins are parallel.

Inflorescences can be a solitary flower or branched or unbranched clusters.
The branches are opposite with the flowers in whorls.

Flowers are bisexual or unisexual then on the same or different plants.
They are on a short or long pedicel with a bracteole at the base.
The 3 green sepals persist in the fruit.
The three, often small petals can be white, purple or pink sometimes with a basal spot.

The 3, 6, 9 or many stamens have anthers that open via long slits.
The superior ovary can be 3 to over 1,000 separate carpels each with 1 (2) ovule with basal placentation.
Each fruit consists of multiple dry achenes or follicles.