Oplismenus compositus, the running mountaingrass, is a species of perennial plant from the family Poaceae that can be found throughout Asia (Pakistan[1] China), Africa, Australia, South America, Mexico[2] and Hawaii.

The leaves are lanceolate, ovate, are 2–16 centimetres (0.79–6.30 in) long and 8–35 millimetres (0.31–1.38 in) wide.

It leaf blades are venated and have obscure cross veins with an apex which is acuminate or slightly acute.

The central inflorescence axis 5–25 centimetres (2.0–9.8 in) long with angular rachis and is either glabrous or pilose on the bottom.

The upper glume is also ovate, but unlike the lower, is also herbaceous with glabrous surface which can be pubescent as well.