Cenchrus echinatus is a species of grass known by the common names southern sandbur,<ref>Template:PLANTS</ref> spiny sandbur,<ref name=BSBI07>Template:Cite web</ref> southern sandspur, and in Australia, Mossman River grass.<ref>Template:Cite web</ref><ref name=au>Cenchrus echinatus. Template:Webarchive National Weeds Strategy.</ref> It is native to North and South America.
It is a clump-forming annual grass growing up to 80 cm tall. The leaves occur with or without hairs and measure up to 12 mm wide. The ligule is a fringe of hairs. The grass has barbed burrs up 4–10 mm long.
In Australia it forms an invasive weed in coastal situations.<ref name=au/>