Mexican feather grass
|Botanical Name||Nassella tenuissima|
|Origin||Southern USA to Chile and Argentina|
IdentificationA densely tufted perennial tussock grass to 1 metre tall. It has hair like leaves and slender wiry stems resembling a dense green fountain. Leaf blades are up to 600mm long and 0.3-0.5mm wide. Leaves are tightly rolled and feel rough when drawn downwardly between the fingers. Its many branched silvery summer infloresnce are 150-250mm long becomes straw coloured in autumn May be distinguished by hairless nodes, some usually visible; the ligule is membranous and hairless, to 2.5 mm long; glumes purplish in the lower half, Flowers have long bent awns giving rise to its name of feather grass
HabitatsGrows on well drained soil and is very drought tolerant.
Impact to Biota and EcosystemsMexican feather grass is an extremely vigorous, invasive plant which crowds out desirable pasture species, reducing stock carrying capacity up to 90%. Nassella forms indigestible balls in the stomachs of stock and if forced to graze it they may lose weight and die, as the plant has a high fibre content and a low nutritive value. It can also crowd out native grasses in coastal or open areas
Dispersal Routes, Vectors, Infestation SourcesHas been used as an ornamental by the garden industry. Seeds are also spread by machinery, in hay, water, mud and in the droppings of animals. Produces thousands of seeds, which are dispersed by wind, water or contaminated soil. Usually propagated from seed and often self sows Normally flowers and seeds between November and January.
The most commonly used and effective control method is grubbing, which is adequate provided the base of the tussock is removed completely and this is carried out before plants are flowering and/or seeding. Herbicides such as Dalapon or Glyphosate are also used but are not nearly as effective as grubbing.
Glyphosate is used in some situations but is ineffective on large plants. Physical control is the most effective control method.
It is important that land management practices enable ready detection and eradication. Every effort should be made to prevent plants seeding, especially on new sites, and to prevent the spread of seed by the movement of livestock, produce, machinery and soil.
In the past Mexican feather grass has been sold widely in garden centres and is still occasionally found in markets.
This plant is prohibited from propagation, sale and distribution throughout New Zealand.