Lo'ulu

Pritchardia remota

Description

Pritchardia remota, a variety of lo'ulu and a member of the palm family (Arecaceae), is a tree 13-16 ft (4-5 m) in height with a ringed, wavy trunk about 5.9 in (15 cm) in diameter. The rather ruffled, fan-shaped leaves average 31 in (78.7 cm) in diameter and are somewhat waxy to pale green with a few tiny scales on the lower surface. The flowering stalks are branched, up to 12 in (30.5 cm) long, and have flowers arranged spirally along their hairless length. Below each flower is a bract 0.08-0.1 in (0.2-0.25 cm) long. The flower consists of a cup-shaped and three-lobed calyx (fused sepals), three petals of about 0.2 in (0.5 cm) in length, six stamens, and a three-lobed stigma. The pale greenish-brown fruit is almost globose, 0.7-0.8 in (1.8-2 cm) long, and about 0.7 in (1.8 cm) in diameter. This is the only species of Pritchardia on Nihoa, and it can be distinguished from other species of the genus in Hawaii by its wavy leaves; its short, hairless inflorescences; and its small, globose fruits.

P. remota is a long-lived perennial, and populations have remained stable for several years. Plants with fruit and flowers have been reported in the spring and summer. Phenology may vary somewhat from year to year, depending on rainfall and climatic factors. The means of pollination are unknown, although a variety of insects have been observed visiting the flowers.

Dr. Rooke brought seed of a palm from Nihoa and planted it on the palace grounds in Honolulu in 1858. A Hillebrand specimen, probably collected from this cultivated tree, was used by Odoardo Beccari in 1890 to describe P. remota. Otto Kuntze transferred the species to other genera the next year, resulting first in Washingtonia remota, then the later Eupritchardia remota. In their 1921 monograph of the genus, Beccari and Joseph Rock included the species in Pritchardia, as do the authors of the current treatment.

Habitat

P. remota is unusual among Hawaiian members of the genus in that it occurs in a dry area. Its present distribution on Nihoa may be related to water availability since many plants are found at elevations of 660-896 ft (201-273 m) in valleys and near freshwater seeps by cliffs. Fossil lo'ulu stems have been found near sea level on Oahu, which may indicate that the genus was more widespread before so much lowland habitat was altered for human use. Within the lo'ulu coastal forest community, P. remota assumes complete dominance with a closed canopy and thick layers of fallen fronds in the understory. Plants growing near the groves and in association with single individuals include 'aheahea, 'ilima, popolo, and some 'ohai. Lichens grow on the trunks of the trees. P. remota provides nesting and other habitat for red-footed boobies (Sula sula rubipes ) as well as occasional perching space for brown noddies (Anous stolidus pileatus ), two of the resident seabirds on Nihoa. P. remota is in cultivation in several botanical gardens.

Distribution

P. remota is known from four extant colonies along 530 ft (162 m) of the lengths of each of two valleys that are about 0.4 mi (0.6 km) apart on opposite sides of Nihoa. Most of the populations of P. remota are crowded into scattered, small groves on abandoned agricultural terraces lower in the valleys. A few trees also grow at the bases of basaltic cliffs on the steep outer slopes of each of the two valleys.

Including seedlings, there were 680 plants found in 1977 in scattered groups, of which 387 occurred in West Palm Valley and 293 in East Palm Valley. Earlier totals were somewhat smaller, probably because younger seedlings were not counted. An un-collected palm, no longer extant, was observed growing on Laysan Island and may have been this species.

Threats

P. remota is threatened by extinction from naturally occurring events due to the small number of populations and the plant's narrow range; these factors also create a limited gene pool that could depress reproductive vigor below the level necessary for continued existence of the species.

Rodent predation could prove disastrous for P. remota, since predation of seeds by rodents has reduced the reproductive capacity of other Hawaiian Pritchardia species. Research conducted in 1997 indicates that many species of insects, mostly aliens, feed on the seeds and fruit of several species of Pritchardia in the main Hawaiian Islands. Due to the small numbers of populations and individuals and its limited distribution, this species is threatened by stochastic extinction and reduced reproductive vigor. Flash floods, fires, and human disturbances also pose potential threats.

Conservation and Recovery

P. remota is in cultivation in several botanical gardens. Several mature plants are in cultivation, but seeds are not banked because they do not remain viable in storage. Some of these individuals, however, are descended from at least one generation of cultivated plants; consequently, the genetic makeup of their offspring may differ from Nihoa populations due to different selective pressures. Off-site cultivation is possible, but must be done very carefully to prevent cross-pollination with other members of the genus.

Immediate recovery actions should include collection of additional seeds for further research into long-term seed storage techniques and establishment of additional cultivated populations. An assessment of the feasibility of introducing this palm to Laysan Island should be undertaken and, if deemed advisable, the U. S. Fish and Wildlife Service should proceed with attempts to establish one or more populations on that island. This island is favored for a reestablishment attempt because P. remota is believed to have occurred there in the past. The goal of reintroduction is to permanently reestablish viable populations in stable and secure conditions. Genetic purity of populations is a prime concern, as are habitat carrying capacity, documentation of artificially established populations, and the possibility of introducing pathogens to natural areas.

Contact

U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

Reference

U.S. Fish and Wildlife Service. 1998. "Final Recovery Plan for Three Plant Species on Nihoa Island." U.S. Fish and Wildlife Service, Portland, Oregon. 83 pp.