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.
A sprawling mat-forming grass with creeping stems, sometimes submerged in fast-flowing water, with fine many-branched flowerheads, either open or narrow depending on flowering stage.
Wide variety of wetland and aquatic habitats, also in drier habitats including roadsides, wasteland, grassland and open scrub. Lowland to subalpine.
Sprawling stoloniferous, rooting at the nodes, mat or turf forming grass, 30-60 (100) cm tall. Can be submerged in clear fast-flowring streams/rivers. Leaf blade 1-20 cm long and 1-8 mm wide with an acute tip. Ligule 2-6 mm long, membranous. The flower heads are usually upright or bending upwards in a many-flowered open or contracted panicle 3-28 × 0.5-2.5-(6) cm.
There are several similar sprawling wetland/aquatic grasses. Paspalum distichum has a shorter ligule and paired flower heads, Glyceria species have a boat-shaped leaf tip and cross-veins on the leaf sheath and Alopecuris geniculatus is often acutely bent at the nodes and has a spike-like flower head.
Spring and summer
Summer to autumn
Seed and stolons dispersed by water and contaminated machinery.
Europe, temperate Asia, N. America
Reason for introduction
Can be controlled manually, mechanically or herbicidally depending on situation.
agrostis: Greek name for a kind of grass
Prepared by Paul Champion and Deborah Hofstra (NIWA)
References and further reading
Edgar E. and H. Connor. 2000. Flora of New Zealand. Volume 5. Manaaki Whenua Press: Lincoln, New Zealand.
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.