Alismataceae
A cosmopolitan family of aquatic flowering plants.
The water-plantain family, Alismataceae, contains 20 genera (17 still living and 3 known only from fossils) and 119 species. Altogether, there are 18 extant genera and two fossil genera assigned to the Alismataceae. These flowering plants are found worldwide, but most species live in the temperate regions of the Northern Hemisphere. Nearly all are herbaceous aquatic plants that grow in marshes and ponds. Most members of this family are robust perennials, though some can be annual or perennial depending on water conditions—typically perennial in permanent water and annual in seasonal water, with exceptions. Their stems are either corm-like or produce stolons. Young leaves and those growing underwater are often linear, while older leaves and those above water can be linear, oval, or arrowhead-shaped. Most leaves have a distinct stalk with a sheathed base. The flower cluster is usually compound, with branches arranged in whorls, though some look like umbels and others bear solitary flowers. The flowers are regular and may be bisexual or unisexual. They have three sepals that usually persist on the fruit. The three petals are often showy and white, pink, or purple, sometimes with yellow or purple spots, but they rarely last more than a day. In the genera *Burnatia* and *Wiesneria*, the petals are tiny or even absent in female flowers. Stamens number 3, 6, 9, or many. The ovary sits above the other flower parts and consists of 3 to many free carpels arranged in a single whorl or a clustered head. Each carpel contains 1 (or sometimes 2) ovules that are anatropous. The fruit is a head of small nutlets, except in the genus *Damasonium*. The seeds lack endosperm and have a curved or folded embryo. Several species, especially in the genus *Sagittaria*, produce edible rhizomes. These are grown for human food and animal fodder in southern and eastern Asia, and were also eaten by Indigenous peoples of North America. Most species provide food for wildlife. Some are grown as ornamentals in bog gardens, ponds, and aquariums. In Southeast Asia, the leaves and flower buds of *Limnocharis flava* are eaten as a "poor people's vegetable."
Quick Facts
- Taxon
- Alismataceae
- Type Genus
- Alisma
- Type Genus Authority
- L.
Facts from the source article.
Lore & Background
Most Alismataceae are robust perennials, but some may be annual or perennial depending on water conditions — they are normally perennial in permanent waters, annual in more seasonal conditions, though there are exceptions. The stems are corm-like or stoloniferous. Juvenile and submerse leaves are often linear, while more mature and emerse leaves can be linear to ovate or even sagittate. Most have a distinct petiole with a sheathed base. The inflorescence is usually compound with whorls of branches, though some are umbel-like, and others have solitary flowers. The flowers are regular, bisexual or unisexual. There are three sepals which usually persist in the fruit. Three petals, usually conspicuous, white, pink, purple, occasionally with yellow or purple spots, rarely last more than one day. In Burnatia and Wiesneria the petals are minute and even occasionally absent in female flowers. Stamens are 3, 6, 9 or numerous. The ovary is superior, comprising 3 to numerous free carpels in one whorl or in a clustered head. Each carpel contains 1 (or rarely 2) anatropous ovules. Fruit is a head of nutlets, except in Damasonium. The seeds have no endosperm and a curved or folded embryo. Under the APG III system, the Alismataceae includes three genera formerly members of the Limnocharitaceae. Altogether, there are 18 extant genera and two fossil genera assigned to the Alismataceae.
Reader's Guide
Several species, notably in the genus Sagittaria, have edible rhizomes, grown for both human food and animal fodder in southern and eastern Asia. They were eaten as food by the indigenous peoples of North America. Most have value as food for wildlife. Some are grown as ornamental plants in bog gardens, ponds and aquariums. The leaves and flower buds of Limnocharis flava are eaten in Southeast Asia as 'poor people's vegetable'. The family's significance lies in its dual role as a food source for humans and wildlife, and as ornamental aquatic plants. Its cosmopolitan distribution and adaptability to various water conditions make it a notable group in both natural and cultivated aquatic environments.
Did You Know?
- The family comprises 20 genera (17 extant and 3 fossil) and 119 species.
- Most species are herbaceous aquatic plants growing in marshes and ponds.
- The petals rarely last more than one day.
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