Vallisneria americana aka Eelgrass

Vallisneria americana is a water plant in the frog's-bit family. The family's name is Hydrocharitaceae. People call it tapegrass, wild celery, and American eelgrass. Kew gives its native range as central and eastern Canada south into the United States. It is native to Florida, where it supports water life. It grows in lakes, slow streams, rivers, and bays. It can live in fresh water and brackish water, which is partly salty.

This plant lives for years and grows beneath the water. Its leaves form rosettes, or groups around a central point. The flat, thin blades range from green to brownish red. Their edges have small teeth, and their tips are round. PFAF gives a leaf length of about 3.3 feet [1 metre]. UF/IFAS reports lengths reaching 6 feet [1.8 metres]. Leaves can reach about 0.08 feet [0.025 metres] wide. Plants spread by runners and form beds beneath the water. They also make winter buds that store energy.

Separate plants bear male and female flowers. PFAF gives the bloom season as July to September. A long, coiled stalk lifts each female flower to the surface. Tiny male flowers form near the plant's base. They break free and float up to the surface. Water brings them to open female flowers, where they supply pollen. Once pollen fertilizes the flower, the female stalk coils. This pulls the flower beneath the water. Curved seedpods then form, each with hundreds of tiny seeds. Both sexes must grow together to make seed.

Grow this plant in a large aquarium or deep outdoor water. PFAF says it needs sun and cannot grow in shade. Its roots can grow in sand, loam, or clay. It prefers slightly acid soil. It also accepts neutral or mildly alkaline soil. PFAF lists USDA zones 8–11 but warns of limited hardiness in Britain. It suggests growing it outdoors only in Britain's mildest areas. To make new plants, divide rooted runners during the growing season.

Tapegrass helps hold sediment in place and keeps water clear. Its beds give fish food and shelter. They do the same for invertebrates, or animals without backbones. Manatees eat it too. People grow it in aquariums and use it to restore lakes and estuaries. PFAF says it helps add oxygen to water. It lists young leaves as edible when cooked. PFAF reports no known hazards and no known medicinal uses. The supplied evidence names no specific pests or diseases.