Serrated tussock grass

Nassella trichotoma, the serrated tussock grass, is a long-lived perennial bunchgrass of the Poaceae family native to the temperate grasslands of southern South America, especially Argentina, Uruguay, Chile, and Peru, and a serious invasive weed of pastures in Australia, New Zealand, and parts of Europe. The plant forms dense, hemispherical tussocks twenty to sixty centimetres tall and across, made up of very fine, wiry, inrolled basal leaves that are pale grey-green when young and weather to a distinctive whitish-straw colour. The leaf surfaces feel rough to the touch in only one direction owing to backward-pointing teeth. From spring into summer the tussocks bear loose, drooping, open panicles ten to thirty centimetres long of small one-flowered spikelets bearing slender, bent, deciduous awns. Each plant can shed many thousands of wind-dispersed seeds.