General Description:- Aquatic or marsh herbs, usually perennial.

Leaves:-
1) Alternate or basal, with sheathing at the base.

Flowers:-
1) Hermaphrodite or unisexual, usually bracteate and verticillate in pedunculate
    umbels, racemes or panicles, occasionally long-pedunculate in the leaf-axils.
2) Sepals 3.
3) Petals 3, usually larger than the sepals, often fugacious or deciduous.
4) Stamens. 3-numerous, with elongated filaments;
    a) anthers, opening by longitudinal slits.
5) Carpels, 3-numerous, spirally arranged or whorled, free or connate at the base.
6) Ovules, 1-many;
7) Styles, apical or subventral.

Fruit:-
1) A group of achenes, drupelets or follicles;
2) Seeds without an endosperm; embryo hippocrepiformis

Genus:- ALISMA

Leaves:-
1) Aerial, floating or submerged.

Flowers:-
1) Hermaphrodite, in panicles or occasionally (in small plants) in racemes or
    umbels.
2) Stamens 6.
3) Carpels, numerous (11-28) in a single whorl, free, each with 1 ovule.
4) Styles, subventral.

Fruit:-
1) Fruitlets, achenial, laterally compressed, obovate to elliptical, with a short ventral
    beak.

Key feature:-
1) Carpels 11-28.
2) Fruitlets, achenial, laterally compressed.
3) Leaves, not deeply cordate.

Comments:-
All European species of this family grow in marshes or in shallow water at the edges of lakes, ponds, canals or slow rivers. Most of them, when growing in water, can produce linear, phyllodal submerged leaves which may or may not persist. When growing in relatively dry habitats the plants are usually dwarfed and may be misleadingly different from plants growing in wetter conditions.