Common Name: Spiny Naiad

General Information

Najas marina is an aquatic, herbaceous, perennial plant. A variable plant that grows entirely under water, its bright to pale green foliage is produced on stems up to 80cm long[].
The plant is sometimes gathered from the wild and used for food. It is sold in local markets in Hawaii. The plant is sometimes grow as an aquarium plant.
Throughout most of its range Najas marina is widespread with stable populations and does not face any significant threats. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2019)[].

Known Hazards

None known

Botanical References

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Range

Cosmopolitan, found in most areas of the world, including Britain, but absent from colder regions

Habitat

Fresh or brackish water[]. Ponds, lakes and slowly-moving rivers at elevations up to 2700 metres in China[]. Brackish or highly alkaline waters of ponds and lakes to 1000 metres in America[].

Properties

Weed Potential	Yes
Conservation Status	Least Concern
Edibility Rating
Habit	Perennial
Height	0.50 m
Pollinators	Water
Cultivation Status	Ornamental, Wild

Cultivation Details

Najas marina is a widespread plant growing from the tropical to the temperate zones.
A submerged water plant, succeeding in shallow fresh or brackish water[].
The plant is often found in shallow water in the wild, but can range up to a depth of 6 metres, and it will also occur in alkaline or brackish water. It is mainly found in waters of high temperature, pH, sulphates and high electrolyte concentrations (or in saline sites) on sand, silt, clay with shells and thick organic matter[].
The plant has brittle stems that break easily, but can then produce roots and develop into a new plant[]. It has spread to most areas of the world, where it forms dense mats that choke out other species. It is one of the few species of aquatic weeds capable of colonizing brackish waters (between fresh and salt water)[].
This is one of the few genera of plants where fertilization takes place under the surface of the water[].
Dioecious, male and female plants must be grown if seed is required[].

Edible Uses

Young stems - raw[, , ].

Medicinal

None known

Other Uses

None known

Propagation

Seed - we have no information on this species but suggest sowing the seed in situ as soon as it is ripe if this is possible. Otherwise store the seed in water in a cool place and sow it in situ in the spring.
Division in the growing season[].