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What Is Eel-grass - (Vallisneria spirals)?

Habitat: Grows on mud or sand in sheltered bays and estuaries 

Distribution in Ireland: Coastal Areas

Status: Established 

Family name: Hydrocharitaceae

Reproduction: After the female flowers have been pollinated, the pedicel curls up like a tendril, drawing the young fruit closer to the bed of the stream or pond; thus the name "spiralis". Seeds have not been observed germinating in aquaria. Instead, it most often propagates by runners which can lead to dense stands.  

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Eel-grass

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Eel-grass (with flowers) on mud-flats

The species is an effective invader due to its efficient dispersal, vegetative reproduction, high biomass production, and popularity in the aquarium trade.

It has narrow, linear leaves that range in colour from a pale-green to reddish up to 1m long and up to 1.5cm broad. V. spiralis is monoecious with male flowers carried on long spiral stalks that break away from the plant and float on the water's surface. In the variety V.s, gigantea the female flowers are on stalks (pedicels) up to 1.85 meters in length.

How To Identify Eel-grass?

Common Name: Tapegrass

Leaves: Dark green flat & thin

Size:  Blade width 1.5 cm

Stems: un-branched stems

Flowers: enclosed on separate shoots. 

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Eel-grass root structure

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Eel-grass -Vallisneria spirals ID guide

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Eel-grass is a grass-like aquatic plant native to Northern Africa that forms lush meadows in shallow, sheltered bays and estuaries. These meadows cushion the shoreline from wave energy, delaying the break down of pollutants. 

Eel-grass meadows

Why Is Eel-grass A Problem?

The intertidal seagrass Eel-grass (Vallisneria spirals), which is distributed in intertidal and shallow subtidal zones, is exposed to nutrients from over-enriched land-based discharge and storm water runoff before they can be washed out to sea. Once the plants have established eradication is very difficult. 

Eel-grass colonizes open tidal mud flats, prime foraging grounds for birds.

It slows water currents and traps new sediments.

 

The dense root system binds soil particles, transforming soft mud into a firm bottom layer.

 

These changes destroy essential habitat for shrimp and other small mud-dwelling and burrowing animals, many of which are staple prey items for shorebirds.

European Communities (Birds and Natural Habitats) Regulations 2011 non-native invasive plant species A-Z (Updated 2017)

There are currently 35 invasive plant species listed in the European Communities (Birds and Natural Habitats) Regulations (annex 2, Part 1)...

 

Click on a species from the following list to find out more regarding non-native species subject to restrictions under Regulations 49 and 50.

  1. American Skunk-CabbageLysichiton americanus

  2. Brazilian Giant-RhubarbGunnera manicata

  3. Broad-Leaved RushJuncus planifolius

  4. Cape PondweedAponogeton distachyos

  5. Cord-GrassesSpartina (all species and hybrids)

  6. Curly Waterweed - Lagarosiphon major

  7. Dwarf Eel-GrassZostera japonica

  8. FanwortCabomba caroliniana

  9. Floating PennywortHydrocotyle ranunculoides

  10. Fringed Water-LilyNymphoides peltata

  11. Giant HogweedHeracleum mantegazzianum

  12. Giant KnotweedFallopia sachalinensis

  13. Giant-RhubarbGunnera tinctoria

  14. Giant SalviniaSalvinia molesta

  15. Himalayan BalsamImpatiens glandulifera

  16. Himalayan KnotweedPersicaria wallichii

  17. Hottentot-FigCarpobrotus edulis

  18. Japanese KnotweedFallopia japonica

  19. Large-Flowered WaterweedEgeria densa

  20. Mile-a-Minute WeedPersicaria perfoliata

  21. New Zealand PigmyweedCrassula helmsii

  22. Parrots FeatherMyriophyllum aquaticum

  23. Red AlgaGrateloupia doryphora

  24. RhododendronRhododendron ponticum

  25. SalmonberryRubus spectabilis

  26. Sea-Buckthorn Hippophae rhamnoides

  27. Spanish Bluebell Hyacinthoides hispanica

  28. Three-Cornered LeekAllium triquetrum

  29. WakameUndaria pinnatifida

  30. Water ChestnutTrapa natans

  31. Water FernAzolla filiculoides

  32. Water LettucePistia stratiotes

  33. Water-PrimroseLudwigia (all species)

  34. WaterweedsElodea (all species)

  35. WireweedSargassum muticum

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