Only a few species of grasses are native to the Hawaiian Islands and all are rare or uncommon at best. Pili is one of the largest and was once widespread, possibly the dominant grass covering low elevation hills and plains. This grass is easily recognized by the long, dark brown awns attached to each seed (technically each fruit). The term pili means to cling, adhere, or join, descriptive of the twisting, binding of the awns as the flower head matures.

Pili grass was utilized as thatching by the early Hawaiians and if not in the Islands naturally would likely have been introduced by the early Polynesians.

The seed has a sharp tip with a barb at the end. When on the ground, the awn twists in response to moisture, driving the sharp-pointed seed down into the soil. The seeds easily penetrate clothing and can be annoying if they poke through to your skin.