Palo de Nigua

Cornutia obovata

Description

Palo de nigua, Cornutia obovata, is an evergreen tree that reaches 33-49 ft (10-15 m) in height and 10 in (25 cm) in diameter. The bright green leaves are opposite, simple, obovate, and blunt or rounded at the apex. The lower surface of the leaves is finely hairy with minute, golden, shiny glandular dots. Leaves may be 2-5.5 in (5-14 cm) long and 1.5-3 in (4-8 cm) wide. Three or four prominent, ascending, curved veins are present on either side of the mid-vein. Twigs are four-sided, finely hairy, and brownish when young. The flower cluster is a terminal panicle, 3-12 in (8-30 cm) in length. Flowers are perfect and zygomorphic. The corolla is bluish or purplish, finely hairy outside with long hairs inside. Fruits are a purplish drupe containing three to four seeds. Flowering has been observed between the months of May and July, and fruits are present in September and October. Seedlings have not been observed during status surveys of the species, which is also known as capá jugüerilla.

Habitat

This species is found in the semi-evergreen or evergreen seasonal forest of the subtropical moist forest life zone on limestone hills, at elevations of 500-1,150 ft (150-350 m). Soils in these hills are shallow, well-drained, alkaline and interspersed between outcrops of hard limestone. Mean annual precipitation varies from 60-80 in (150-200 cm). Two strata are present in this type of forest. The upper strata is composed of a continuous layer which extends up to 65 ft (20 m) in height with a few emergent trees reaching 80 ft (25 m). From one-third to two-thirds of the species are deciduous. The second strata reaches 33 ft (10 m) in height and the number of deciduous species is low. Most species are evergreen, with simple, microphyllous leaves. Palm species may be common in this strata. Common species in the upper strata are Bucida buceras (ucar), Bursera simaruba (almacigo), Clusia rosea (cupey), and Tabebuia heterophylla (roble blanco). The under-story includes species such as Eugenia biflora, E. foetida, E. axillaris, Coccoloba diversifolia, and C. microstachya. Other rare and endangered species found within this forest type include the Puerto Rican boa (Epicrates inornatus ), and the plants Zanthoxylum thomasianum, Polygala cowelii, Banara vanderbiltii, and Ottoschulzia rhodoxylon.

Palo de nigua is also found near Barranquitas on Monte Torrecilla, an area which is volcanic in origin and is at an elevation of 3,080 ft (940 m). The vegetation of this area has been classified as lower montane forest in the subtropical moist forest life zone. In this area, palo de nigua is associated with Prestoea montana (sierra palm), Ocotea wrightii (canelon), Guettarda ovalifolia (cucubano), Dendropanax laurifolius, Psychotria berteroana (cachimbo común), Miconia sintenisii (camasey), and Daphnopsis philippiana (emajagua de sierra).

Distribution

Palo de nigua is endemic to the island of Puerto Rico. Only seven trees are known to exist in three areas: five individuals from five different locations in the limestone hills of the Rio Abajo Commonwealth Forest, one from the limestone hills near the Arecibo Observatory, and one from Barranquitas in the central mountains. Although not found in recent years, the species has been reported from serpentine soils in the Susua Commonwealth Forest in the southwestern part of Puerto Rico.

Threats

Historically, deforestation and selective cutting for agriculture, grazing, production of charcoal, and the cutting of wood for construction materials have affected palo de nigua. In addition, coffee was planted abundantly in the central mountain area. As of the late 1990s, urban and tourist expansion was encroaching on previously inaccessible areas. The construction of communication facilities had resulted in the elimination of forest vegetation on the higher peaks, such as Monte Torrecilla, where C. obovata was located. Forest management practices, where implemented without consideration of the species, may adversely affect the species in the Rio Abajo Commonwealth Forest.

Conservation and Recovery

Populations found on privately owned land should be given protection through conservation easements or acquisition. Protection of the species is under the management of the Rio Abajo Commonwealth Forest. Propagation for introduction into protected areas for the establishment of new populations or enhancement of existing 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
http://southeast.fws.gov/

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

References

U. S. Fish and Wildlife Service. 1988. "Determination of Endangered Status for the Plant Cornutia obovata (Palo de Nigua)." Federal Register 53 (67): 11610-11612.

U. S. Fish and Wildlife Service. 1992. " Recovery Plan for Cornutia obovata and Daphnopsis hellerana. " U. S. Fish and Wildlife Service, Atlanta. 22 p.

Vivaldi, J. L., and R. O. Woodbury. 1981. "Status Report on Cornutia obovata. " Status report submitted to the U. S. Fish and Wildlife Service, Mayaguez, Puerto Rico. 35 p.