''Aristida chaseae'' is a rare species of

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

known by the common name Chase's threeawn. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

, where it is known from two locations in the Cabo Rojo National Wildlife Refuge and the Sierra Bermeja.USFWS
Determination of Endangered Status for Three Puerto Rican Plants.
''Federal Register'' April 27, 1993. It is a federally listed

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

of the United States. It cannot compete with

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived there ...

of grasses, such as '' Brachiaria subquadripara'', which are invading its habitat. This is a perennial grass producing a tuft of stems up to half a meter high or a bit taller. Plants occurring in the deep soils of Cabo Rojo tend to be more robust than those growing in the poorer soils of the Sierra Bermeja.Silander, S. (1995)
Sierra Bermeja Plants Recovery Plan.
USFWS. Cabo Rojo plants occur in coastal

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

habitat, and those in the Sierra grow in acidic clay soils with many rocky outcrops. Development of the Sierra Bermeja is a potential threat for the grass and many other endemic plant species.

References

External links

USDA Plants Profile
chaseae Endemic flora of Puerto Rico {{Poaceae-stub