Pelos del Diablo

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Pelos del Diablo

Aristida portoricensis

ListedAugust 8, 1990
FamilyPoaceae (Grass)
DescriptionTufted grass, growing in bunches.
HabitatSerpentine slopes and red clay soils.
ThreatsResidential development; mining.
RangePuerto Rico


The tufted culms (stems) of pelos del diablo (Aristida portoricensis ), an endemic perennial grass, may reach 11.8-19.7 in (30-50 cm) in height. These culms occur in large bunches and are slender, erect, or spreading at the base. The blades are involute, somewhat curved, 2-3.9 in (5-10 cm) long, and scarcely 0.04 in (1 mm) wide when rolled. The panicles (flower clusters)from 1.2-3.1 in (3-8 cm) in lengthare narrow, loose, and few-flowered. The few, distant branches are stiffly ascending and mostly floriferous (bearing flowers) from the base. The glumes (leaves on the floral axis) are awn-pointed, the first about 0.3 in (7 mm) long, the second approximately 0.4 in (10 mm) in length. The lemma (lower bract enclosing the flower) is from 0.4-0.5 in (10-12 mm) long, including the 0.04-in-long (1-mm-long) callus and the 0.08-to 0.1-in-long (2-to 3-mm-long), slightly twisted, scabrous neck. The awns (leaf-ending bristles) are almost equal, divergent, or horizontally spreading, 0.8-1.2 in (2-3 cm) long, and slightly contorted at the base. Little is known about the reproductive biology of this species.


Pelos del diablo is found on serpentine slopes and red clay soils of southwestern Puerto Rico. In the Sierra Bermeja this grass is found growing on exposed rock crevices, frequently in association with A. chasae (an endangered species) and Digitaria eggersii at elevations of 591-988 ft (180-301 m).


Pelos del diablo is endemic to Puerto Rico and is currently known from only two locationsCerro Las Mesas and the Sierra Bermeja in the southwestern part of the island. The species was first collected in 1903 from the Cerro Las Mesas site. It was later reported from the Guanajibo area and then from Hormigueros, both in southwestern Puerto Rico; however, these populations appear to have been eliminated as a result of urban and commercial development. The Sierra Bermeja site was recently discovered.


This species was apparently eliminated from two historic locations, Guanajibo and Hormigueros, as a result of urban and residential expansion. The Cerro Las Mesas site is surrounded by residential development and is currently threatened by the expansion of these areas.

In the Sierra Bermeja, tourist and residential development as well as agricultural activity, particularly grazing, threaten the species. Land clearing occurs frequently in order to enhance grazing operations. In addition, mining for gold and copper has been proposed for the Sierra Bermeja.

Conservation and Recovery

Habitat protection, through acquisition or conservation easements, should be considered for both known population sites. Recommendations for management include successional retardation, studies to evaluate the role of fire and competition from introduced grasses, and artificial and natural regeneration studies in order to evaluate the feasibility of the establishment of new populations in protected areas.


U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345 T
elephone: (404) 679-4000

Boquerón Ecological Services Field Office
P.O. Box 491
Boquerón, Puerto Rico 00622-0491
Telephone: (787) 851-7297
Fax: (787) 851-7440


Department of Natural Resources. 1989. "Natural Heritage Program Status Information on Aristida portoricensis. " San Juan, Puerto Rico.

Liogier, H.A., and L.F. Martorell. 1982. Flora of Puerto Rico and Adjacent Islands: A Systematic Synopsis. University of Puerto Rico, Rio Piedras, Puerto Rico.