Zostera marina aka Eelgrass

Zostera marina, or eelgrass, belongs to the Zosteraceae family. It is a perennial, so it lives for many years. It grows in shallow sea water in temperate regions. Kew lists western California as part of its native range. The RHS says it is native to Britain and Ireland too. Plants For A Future records it across Europe, Asia and North America.

The plant grows to about 3.3 feet [1 metre] tall. It has rhizomes, which are stems that grow below ground. These help it keep growing beneath the water year after year. It grows on sea floors of fine gravel, sand and mud. Plants For A Future places it from the low spring-tide mark downwards. That source records plants as deep as 13 feet [4 metres]. It also says the plant is rare in estuaries.

Flowers appear from June to September. The seeds ripen from August to October. Each plant has both male flowers and female flowers. These flowers are separate, and water carries pollen between them. Seeds offer one way to grow new plants. Plants For A Future says to sow them soon after they ripen. Growers can also divide the plant to make new plants.

Eelgrass needs an open site with no shade. It grows in sand or loam beneath sea water. It can grow in mildly acid soil or neutral soil. It can grow in mildly alkaline soil too. Salty ground forms part of the place where it grows. Its need for sea water rules out most normal garden sites. Treat it as a sea-water plant, not a standard pond choice. The sources give no hardiness zone or advice on pests.

Plants For A Future lists several uses for food. People eat the leaves raw or cooked. The crisp leaf bases taste sweet. The source says Indigenous North American people used them at feasts. It lists seeds as food but gives no steps to prepare them. People chewed roots for sweet juice and used them to add flavour. They also dried roots for winter food and ate raw rhizomes. The source lists no known hazards. This does not mean it gives a full safety review. It records old uses of leaves as remedies. It gives no proof here that those remedies work. People have used dried leaves and stems to pack things. They have also used the plant as manure. These uses give it value beyond its role in the sea.