Aristida chaseae is a rare species of grass known by the common name Chase's threeawn.

It is endemic to Puerto Rico, where it is known from two locations in the Cabo Rojo National Wildlife Refuge and the Sierra Bermeja.

[1] This is a perennial grass producing a tuft of stems up to half a meter high or a bit taller.

[2] Cabo Rojo plants occur in coastal grassland habitat, and those in the Sierra grow in acidic clay soils with many rocky outcrops.

[2] Development of the Sierra Bermeja is a potential threat for the grass and many other endemic plant species.