Encyclopedia - Plants for ponds
Water-plantain
Alísma
Plants for a pond
Water-plantain, or water-shilnik, or alisma (lat. Alísma) — a genus of perennial herbaceous plants of the family Water-plantains (Alismataceae). There are about ten species widely distributed around the world (mostly in the Northern Hemisphere). Six species of Alisma are found in the territory of the former USSR.
The scientific name of the genus has ancient Greek origins and comes from the name of an aquatic plant mentioned by Dioscorides in his work "On Medicinal Substances" (lat. De materia medica, I century AD). The synonymy of the genus includes the name Plantaginastrum Heist. ex Fabr. (1759).
Because of its similarity to some species of plantain (Plantago), Alisma is sometimes called "water plantain" (but more often this name is applied only to the species Alisma plantago-aquatica). Occasionally the name "vahtovnik" is used.
Species of Alisma are widespread in the temperate regions of the Northern Hemisphere, as well as in Southern Africa. Some species occur in the tropics of Southeast Asia, Australia, eastern and southern Africa, and Central America. All members of the genus are aquatic and marsh plants.
Members of the genus are perennial (rarely annual) herbaceous plants.
The rhizome is very short and thick. Leaves with long petioles are gathered in basal rosettes. Alisma is characterized by marked heterophylly: submerged leaves are linear with parallel venation; aerial leaves have a lanceolate or ovate blade with a cuneate or cordate base and campylodromous venation (in this type of venation the lateral veins depart only from the midrib and are directed toward the leaf margin).
Scapes arise from the center of the leaf rosettes. Flowers are actinomorphic with a double perianth. There are three sepals, they are greenish and remain on the fruits. There are also three petals; they are free, deciduous; white or pinkish-white; in plants growing under water the petals are sometimes underdeveloped. Flowers are bisexual, with six stamens and numerous carpels situated on an almost flat receptacle. Each carpel contains one ovule. Flowers are arranged in whorls in the axils of bracts (foliage of the inflorescence zone); gathered into a pyramidal paniculate inflorescence, in the whorls of which there may be from 3 to 11 branches.
The fruits are small, laterally flattened many-nutlets of green color; on the back they have one or two grooves; they disintegrate into floating segments (nutlets), each of which contains one seed.
Some Alisma species are used in ornamental gardening — they are planted along pond edges or in marshy areas of gardens and parks; the plants are valued also because they practically require no maintenance. Propagation is by seeds and division.
The rhizome of the common water-plantain (Alisma plantago-aquatica) is rich in starch and edible after thermal processing (for example, baked).
Water-plantain serves as food for muskrats and ducks.
Location: not demanding regarding growing conditions, tolerates poor clay or sandy soils, can grow in sun and partial shade. Suitable for planting in damp clay places and on pond banks up to a depth of 15 cm.
Planting: planted at a depth of 5-15 cm.
Propagation: by seeds, which can be sown in autumn or spring into moist substrate, as well as by division of the clump throughout the summer.