Nassella trichotoma (Nees) Hack. ex Arech.
Family Poaceae, Tribe Stipeae
Spikelets of 1 fertile floret. Glumes similar, narrowly lanceolate, very long-tapered, hyaline, with 3 scabridulous nerves, up to 3½ times as long as floret; 4–10 mm long. Floret laterally compressed; outline obovate, with truncate apex; lemma coriaceous, rolled up longitudinally, concealing palea, surface tuberculate, crown 0.5 mm long; callus bearded with hairs half as long as floret; lemma awn off-center, 15–35 mm long, straight to geniculate and twisted, antrorsely barbed. Caryopsis laterally compressed, narrowly obovate to oblong or rhombic, 1.2–1.6 mm long, hilum linear.
Nassella exserta Phil. (=Nassella gigantea (Steud.) Muñoz-Schick) [no image available] (non-FNW)
Africa: South Africa; Europe: United Kingdom, France, Italy; Oceania: Australia, Tasmania, New Zealand; South America: Argentina, Brazil, Chile, Peru, Uruguay
native to South America
subhumid, subtropical, and warm-temperate regions, rocky hillsides
Nassella trichotoma is a perennial tussock-forming grass, to 60 cm tall. In its native range, it is heavily grazed by cattle, horses, and sheep, but in Australia, it is a serious weed, primarily responsible for the reduced carrying capacity of pasture. Sheep will eat it non-preferentially, but they lose weight, and may be injured by the awns. Dense infestations of tussocks form, eventually eliminating other plants. Propagation is by grain alone, and these remain viable after passing through animals and in the soil for up to 15 years. The florets are dispersed by wind, and cling to wool and clothing.