Chilean needlegrass

Nassella neesiana, the Chilean needle grass or Chilean speargrass, is a tussock-forming perennial cool-season grass in the Poaceae family native to the temperate grasslands and pampas of southern South America, including Argentina, Chile, Uruguay, southern Brazil and Bolivia. Plants form dense, long-lived tufts 30 to 100 centimetres tall, with narrow, flat to inrolled, green to bluish-green leaf blades and slender, wiry culms. From late spring through summer the stems carry loose, nodding, somewhat purple-tinged panicles 10 to 30 centimetres long; each spikelet bears a single floret tipped with a long (5 to 9 centimetre), twice-bent, twisted awn that detaches with the sharp-pointed mature caryopsis. These needle-like diaspores cling tenaciously to wool, fur and clothing and can mechanically injure livestock. The species also produces hidden cleistogamous florets within the leaf sheaths. Widely introduced for pasture, it has become a serious invasive weed of temperate grasslands in Australia, New Zealand, southern Europe and parts of North America.