Higuero de Sierra

Crescentia portoricensis

Description

Higuero de Sierra, Crescentia portoricensis, is an evergreen vine-like shrub or small tree growing to a maximum height of 20 ft (6.1 m) and attaining a trunk diameter of 3 in (7.6 cm). Vine-like branches and stems spread onto surrounding foliage. The bark is gray and the branches long and slender. The shiny, oblanceolate to narrowly elliptic leaves are dark green and leathery, usually clustered at the stem nodes. Tubular flowers are pale yellow and irregularly bell-shaped. The two-lobed, tubular calyx is leathery; the corolla is yellowish-white with the petals forming a bell-shaped tube. The fruit is dark green, cylindrical, hard, and dry.

Habitat

Higuero de Sierra is endemic to serpentine soils in evergreen, semi-evergreen, and deciduous forests in the lower Cordillera region of the western mountains of Puerto Rico. The Susua Forest is found within the subtropical moist forest life zone, the most extensive life zone found on the island. The Maricao Forest is found within the subtropical moist and wet forest zones. The majority of the area of these forests is covered by serpentine outcrops interspersed with clay soils. The topography is mountainous in both forests, with steep ravines and intermittent streams.

Higuero de Sierra grows beside streams in silty bottomland and is adapted to moderate levels of flooding. In recent years the severity of floods has increased because of land clearing and deforestation of the drainage basin. Stream banks have been undercut by flood waters, causing collapse with loss of plants.

Distribution

The species was first found in 1913 along the Maricao River in western Puerto Rico. A small population was later found in the Susua area 10 mi (16.1 km) to the southwest. Before 1979 the species was known from two small populations in Maricao Commonwealth Forest and a third in Susua Commonwealth Forest, each comprising six or eight mature trees. Both Maricao Forest sites were recently lost to flash flooding and erosion.

Six populations were discovered in the Maricao River Valley with a total of 36 mature individuals; there are six surviving Susua Commonwealth Forest plants, bringing the total number of known shrubs to 42. No seedlings or other evidence of natural reproduction has been observed at any of the six sites, and botanists assume that flash floods are preventing the establishment of new plants.

Threats

Widespread deforestation during the early part of the century, especially at elevations below 1,550 ft (472.4 m), is mainly responsible for the decline of Higuero de Sierra. Further clear-cutting at higher elevations would increase the force of flooding and erosion-induced landslides in the valleys where shrubs survive. In the Maricao Commonwealth Forest, all populations are threatened by increasing erosion as a result of deforestation and poor management practices upstream. The six known individuals in the Susua Forest population are located close to a heavily traveled access road, and to trails that make them more accessible. They are also located on a steep stream bank and are threatened by erosion and flash flooding.

Conservation and Recovery

The U. S. Army Corps of Engineers has proposed several flood control projects in the mountains, which could significantly improve survival chances for the Higuero de Sierra at some sites, while inundating other former sites. The Corps will consider the welfare of Higuero de Sierra when designing its projects as is required by provisions of the Endangered Species Act. Dialogue with the U. S. Fish and Wildlife Service on the proposed projects has been initiated.

In 1989 both cuttings and fruits were collected for propagation at the Fairchild Tropical Gardens in Miami. Germination of seeds was successful.

Contacts

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

U. S. Fish and Wildlife Service
Caribbean Field Office
P.O. Box 491
Boquerón, Puerto Rico 00622

References

U.S. Fish and Wildlife Service. 1987. "Determination of Higuero de Sierra, Crescentia portoricensis, to Be an Endangered Species." Federal Register 52(233): 46085-46087.

U.S. Fish and Wildlife Service. 1989."Draft Recovery Plan for Higuero de Sierra, Crescentia portoricensis. U.S. Fish and Wildlife Service, Atlanta. 32 pp.

Vivaldi, J. L., and R. O. Woodbury. 1981. "Status Report on Crescentia portoricensis Britton." Report.U.S. Fish and Wildlife Service, Atlanta.