blue sweet grass, glaucous sweet grass
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 in and on the margins of freshwaters, on damp ground and swamps. It is characterised by its grey/green leaf blades, and ability to form loose floating mats in shallow water.
Throughout New Zealand, including Stewart Island and Chathams.
Aquatic in drains and other slow flowing water bodies. Damp ground in swamps and pastures, drains and river banks.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland).
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Perennial marginal aquatic grass with rather flaccid culms (15)-25-45 cm. Leaf blade (4)-8-17 cm, folded at first then becoming flat. Panicle 20-30-(40)cm.
Very similar to Glyceria fluitans. 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. Seed is produced but is probably not viable for more than one season.
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.
Can tolerate very damp ground, or swampy conditions.
glyceria: From the Greek glykos ‘sweet’.
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Champion et al (2010). An illustrated guide to common grasses, sedges and rushes of New Zealand. NZ Plant Protection Society Inc, 182pp.
Coffey BT, Clayton JS (1988). New Zealand water plants: a guide to plants found in New Zealand freshwaters. Ruakura Agricultural Cente. 65pp.
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.