Vascular – Exotic
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
Aquatic perennial emergent grass found on the margins of freshwaters on damp ground and swamps. It is characterised by its bright green leaf blades, and ability to form loose floating mats in shallow water.
Throughout New Zealand.
Aquatic in drains and other slow flowing waterbodies. Damp ground in swamps and pastures, drains and river banks.
Wetland plant indicator status rating
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Perennial marginal aquatic grass, loosely tufted or forming loose masses in shallow water. Culm (20–)45–75 cm, erect or spreading, sometimes prostrate or floating at base. Leaf-blade bright green 10–23 cm, folded at first then becoming flat. Panicle (20–)30–55 cm.
Very similar to Glyceria declinata. These two species can be distinguished when flowering as G. declinata has 3–5 distinct teeth on the lemma apex and the palea teeth exceed the lemma apex. G. fluitans has a rounded lemma and the palea does not exceed the lemma. G. maxima is a taller species, which has a distinct pointed ligule.
Perennial. Seed and vegetative fragment spread by water movement. Reproduces by seed and rhizomes. Each flower head consists of an open panicle with 20–30 spikelets containing many seeds.
Seed and stem fragments spread within catchment via water flow. Contaminated diggers, livestock, soil movement, dumped vegetation, eel nets boats and trailers all spread seed and rhizomes into new catchments.
Europe and North America.
Reason for introduction
Pasture species, or contamination of other grass seed
Can be controlled manually, mechanically or herbicidally depending on situation.
Tolerant of very damp ground, physical damage, grazing, cold temperatures, and high nutrient levels. Intolerant of shade.
glyceria: From the Greek glykos ‘sweet’.
fluitans: From the Greek fluito (floating)
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Coffey BT, Clayton JS. 1988. New Zealand water plants: a guide to plants found in New Zealand freshwaters. Ruakura Agricultural Centre, Hamilton, NZ. 65 p.
Johnson PN, Brooke PA. 1989. Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington, NZ. 319 p.
Champion P, James T, Popay I, Ford K. 2012. An illustrated guide to common grasses, sedges and rushes of New Zealand. NZ Plant Protection Society Inc, Christchurch, NZ. 182 p.