Schiedea verticillata

No Common Name

Description

Schiedea verticillata is a perennial herb of the pink family (Caryophyllaceae) that dies back to an enlarged root during dry seasons. The upright or sometimes pendent stems can reach 1.3-2 ft (0.4-0.6 m) in length. The stalkless leaves are fleshy, broad, and pale green; usually arranged in threes; and measure 3.5-5.9 in (8.9-15 cm) in length and 2.8-3.5 in (7.1-8.9 cm) in width. Flowers are arranged in open, branched clusters, usually 6.7-9.8 in (17-24.9 cm) long.

Opposite or whorled pale green bracts, located at inflorescence branches and underneath the flowers, measure 0.2-1.6 in (5.1-41 mm) long at the central branch and 0.1-0.2 in (2.5-5.1 mm) long on the side branches and underneath the flowers. Each petalless flower is positioned on a stalk 0.2-0.8 in (5.1-20.3 mm) long and has five lance-shaped sepals 0.3-0.4 in (7.6-10.2 mm) long, five nectaries, ten stamens, and four or five styles. The ovoid capsule measures 0.3-0.4 in (7.6-10.2 mm) long and releases reddish to grayish brown seeds that are about 0.03 in (0.8 mm) long. This species, the only member of its genus to grow in the northwestern Hawaiian Islands (specifically Nihoa), is distinguished from other species of the genus by its exceptionally large sepals and by usually having three leaves per node.

S. verticillata produces more seeds and more nectar than any other species in its genus and has the highest degree of genetic diversity between individuals. S. verticillata is a short-lived perennial in which the reproductive cycle may not be seasonal; many life-stages of the plant have been found simultaneously throughout the year. Research indicates that the plants flower, set, and disperse seed in a relatively short period of time, although the means of pollination are unknown.

The first specimens of S. verticillata were collected near Derbys Landing in 1923 and described in 1931. The epithet refers to the verticillate (whorled) arranement of the leaves. Although the species was transferred to the genus Alsinidendron in 1944, current taxonomists consider it to be a species of Schiedea.

Habitat

S. verticillata typically grows in soil pockets and cracks on coastal cliff faces at elevations between 100-890 ft (30.5-271.3 m). Associated species include 'aheahea, pohuehue, koali 'awa, kupala, kawelu, and lichens on surrounding rock.

Distribution

All historically known colonies of S. verticillata on Nihoa are known to be extant. Colony locations and levels appear to have shifted somewhat, but total numbers have remained relatively stable for several years. Six populations of 385-414 total individuals were counted between 1980-83. In 1992 service refuge staff counted only 170-190 plants in all six populations; however, a total of 359 plants in 10 populations were counted in 1996. These were distributed primarily on the western half of the island, although a population of 13 plants was seen on the east spur of the island near Tunnel Cave. Two previously unobserved populations with respective numbers of two and 99 plants were noted on the north cliffs above Miller's Valley. Other populations included 24 plants at Dog's Head, 37 at Devil's Slide, 10 near Miller's Peak, a previously unknown occurrence of 62 on the ridge separating West and West Palm valleys, 80 near lower West Valley, 28 near Pinnacle Peak, and four northeast of Pinnacle Peak.

Threats

Although recent plant numbers appear to be stable, this species may have experienced a historical reduction in total population due to disturbances resulting from Polynesian settlement of Nihoa. Alien plant and insect species on the island may be posing threats. Rodent predation could prove disastrous for S. verticillata, since rodents may feed on its fleshy root. It is also threatened by stochastic extinction and reduced reproductive vigor due to its very restricted range, small numbers, and the vulnerability of plants to disturbance events in their steep, rocky habitat. Fire and other human disturbances also pose potential threats.

Conservation and Recovery

Waimea Arboretum has six plants, all propagated as cuttings from a single parent plant. The National Tropical Botanical Garden has 250 seeds in storage but none in cultivation. The University of California at Irvine has nine plants in cultivation. Cultivation of this species has been hampered in the past by die-offs of seedlings, termed "damping off," due to a fungal disease. However, this problem can probably be controlled by using sterile soil and maintaining cool conditions with low humidity during and after germination.

Immediate recovery actions should include collection of seeds and cuttings to establish additional cultivated populations. If research indicates that it is feasible and desirable to introduce this species outside of its historic range, Necker Island should be considered since it is adjacent to Nihoa, has a similar habitat, and is protected as a service refuge. Kilauea Point and Midway Atoll National Wildlife Refuges should also be assessed for suitability since they are protected areas, have plant nursery facilities, and have full-time staff. Midway has a similar climate to Nihoa, and Kilauea Point has north-facing cliffs similar to Nihoa.

Contacts

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/

Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P. O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-1201
Fax: (808) 541-1216

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.