Leptocereus grantianus

No Common Name

Description

A sprawling or suberect and nearly spineless cactus, Leptocereus grantianus may reach up to 6.6 ft (2 m) in height and 1.2-2 in (3-5 cm) in diameter. Its elongated stems have from three to five prominent ribs with broadly scalloped edges. Ribs of young joints are thin, and the small areoles or spine-bearing areas may bear one to three minute spines that are nearly black and disappear as the joints grow older. The flowers are solitary at terminal areoles, 1.2-2.4 in (3-6 cm) long, and nocturnal. The outer perianth segments are linear, green, and tipped by an areole like those of the tube and ovary. The inner perianth segments are numerous, cream-colored, oblong-obovate, obtuse, and about 0.3 in (8 mm) long. The fruit is subglobose to ellipsoid and about 1.6 in (4 cm) in diameter.

Habitat

L. grantianus is located close to the shoreline on the steep and crumbling rocky banks of Culebra Island, a subtropical dry forest life zone. Mean annual rainfall ranges from a minimum of 23.6 in (600 mm) to a maximum of 39.4 in (1,000 mm) in this life zone. The vegetation tends to form a complete ground cover and is almost entirely deciduous on most soils. Leaves of surrounding trees are often small and succulent or coriaceous, and species with thorns and spines are common. Tree heights do not usually exceed 49 ft (15 m) and crowns are typically broad, spreading, and flattened. Fire is common, and successional vegetation is composed mainly of grasses.

Associated species include sea grape (Coccoloba uvifera ) and almacigo (Bursera simaruba ).

Distribution

L. grantianus is endemic to the island of Culebra, located just off the northeastern corner of Puerto Rico. Only one population, consisting of approximately 50 individuals, occurs along the rocky coast near Punta Melones.

Threats

Historically, grazing, production of charcoal, deforestation and selective cutting for agriculture, and the cutting of wood for construction materials have affected dry forest vegetation. At the end of the twentieth and the beginning of the twenty-first centuries, the island of Culebra was subject to intense pressure for residential and tourist development. Land adjacent to the population was proposed for the development of a housing project.

The ornamental potential of the species may lead to overcollection in the future. The steep rocky banks along the shoreline of Culebra are unstable; therefore, natural events such as hurricanes might result in the complete elimination of the only known population of L. grantianus.

Conservation and Recovery

This population might be given protection through conservation easements or acquisition. Propagation for introduction into protected areas (to establish new populations) should be considered a priority recovery mechanism. Preliminary efforts at propagation indicate that the species roots easily from cuttings.

Contacts

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

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

References

Britton, N. 1933. "An undescribed cactus of CulebraIsland, Puerto Rico." Cactus and Succulent Society of America 5: 469.

Procter, G. R. 1991. "Status report on Leptocereus grantianus Britton." In Puerto Rican Plant Species of Special Concern, Status and Recommendation. Publicacion Cientifica Miscelanea No. 2. Department of Natural Resources, San Juan.

U. S. Fish and Wildlife Service. 1993. "Determination of endangered status for the plant Leptocereus grantianus. " Federal Register 58: 11550.