South America
Serrated tussock (Nassella trichotoma (Nees) Hackel ex Arech, Poaceae) is a perennial bunch grass native to South America. It mainly occurs in warm temperate grasslands where it is native. Serrated tussock is unpalatable pasture grass, and considered a major weed in Australia and South Africa (CABI 2019, Humphries et al 2020). In the United States, serrated tussock is on the USDA invasive weed list and exists in the following states: Illinois, Kentucky, North & South Carolinas, Arizona, Florida, Hawaii, and Texas (Flora of North America 2021, USDA-NRCS 2004). Serrated tussock has not yet been observed in California.
Serrated tussock forms tussocks up to 50 cm tall and 25 cm across at the base, and has fibrous roots at the base (CABI 2019). It is mainly used as an ornamental grass (CABI 2019).
How to ID N. trichotoma: https://www.youtube.com/watch?v=EOz_V5E46t8
Management: https://www.youtube.com/watch?v=xIrcG1LdvAM
Serrated tussock was accidentally introduced in Australia and South Africa in the 1900s and cultivated as an ornamental grass (Weeds Australia 2021).