Schiedea nuttallii

No Common Name

Description

Schiedea nuttallii, a generally hairless and erect subshrub of the pink family, has stems normally 1-5 ft (0.3-1.5 m) long and internodes usually 0.3 to 1.6 in (0.8-4 cm) long. The green, sometimes purple-tinged, opposite leaves are narrowly egg-shaped or lance-shaped to narrowly or broadly elliptic, 2-4 in (5-10.2 cm) long, and 0.6-0.8 in (1.5-2 cm) wide. The apetalous, perfect flowers are borne in open branched inflorescences, normally 8-10 in (20.3-25.4 cm) long. The lance-shaped sepals, 0.08-1.5 in (0.2-3.8 cm) long, are green or sometimes purple-tinged. The fruit is a capsule; its round to kidney-shaped seeds are about 0.04 in (0.1 cm) long. This species is distinguished from others in this endemic Hawaiian genus by its habit, length of the stem internodes, length of the inflorescence, number of flowers per inflorescence, smaller leaves, smaller flowers, and smaller seeds.

Plants on Makua Military Reservation have been under observation for ten years, and they appear to be long-lived. S. nuttallii appears to be an outcrossing species. Under greenhouse conditions, plants fail to set seed unless pollinated, suggesting that this species requires insects for pollination. Seedlings of Schiedea occurring in mesic or wet sites are apparently consumed by introduced slugs and snails. These have been observed feeding on S. membranacea, another mesic forest species occurring on Kauai. In contrast to mesic forest species, Schiedea occurring in dry areas produce abundant seedlings following winter rains, presumably because there are fewer alien consumers in drier sites.

Individuals from Keawapilau Gulch are genetically diverse and probably would suffer from severe inbreeding depression if forced to inbreed.

In 1834, Thomas Nuttall collected a specimen of S. nuttallii in the Koolau Mountains of Oahu. William Hooker described this species ten years later. Other published names considered synonymous with S. nuttallii include S. nuttallii var. lihuensis and S. oahuensis.

Habitat

S. nuttallii typically grows in diverse lowland mesic forest, often with 'ohi'a (Metrosideros collina ) dominant, at elevations usually between 1,360 and 2,400 ft (414.5 and 731.5 m). The population on Kauai is found at 2,590 ft (789.5 m) in elevation. Associated plant species include hame (Antidesma platyphyllum ), kopiko (Psychotria sp.), olomea (Perrottetia sandwicensis ), papala kepau (Charpentiera sp.), and Hedyotis acuminata (au).

Distribution

S. nuttallii was known from scattered historical locations on southeastern Kauai, Oahu, Molokai, and Maui.

The statewide total of six populations contained between 40 and 100 S. nuttallii individuals in 1997, of which 10-50 were on Kauai and 30-50 were on Oahu.

The two Kauai populations occur on private land east of Haupu Peak and in Limahuli Valley. Four populations are found on Oahu: one population of 28 plants in Kahanahaiki Valley on the army's Makua Military Reservation; two populations of an unknown number of plants within the state-owned Pahole Natural Area Reserve; and one population of two plants on private land in Ekahanul Gulch on Honouliuli Preserve.

Threats

S. nuttallii faces serious threats to its survival from habitat degradation and destruction by feral pigs and goats, and possibly deer on Kauai; competition with several alien plants; landslides; predation by the black twig borer; slugs and snails; fire from military activities; and a risk of extinction from either random natural events or reduced reproductive vigor due to the small number of populations and individuals remaining.

One population of S. nuttallii on Oahu is threatened by pigs. Goats threaten the one population of S. nuttallii on Kauai.

Military training exercises, troop ground maneuvers, and helicopter landing and drop-off activities on Oahu could trample or flatten S. nuttallii individuals that occur on land leased or owned by the Army.

Collecting for scientific or horticultural purposes and visits by individuals avid to see rare plants are potential threats to this endangered species.

Silk oak (Grevillea robusta ) threatens one population of S. nuttallii in the Waianae Mountains of Oahu, while common guava threatens the largest population of S. nuttallii in the same mountains.

Fire poses a potential threat to populations of S. nuttallii. On Oahu, unintentionally ignited fires have resulted from military training exercises in Makua Military Reservation and Schofield Barracks Military Reservation and pose a possible threat to populations of S. nuttallii that grow in dry and mesic forest on these lands. Accidentally or maliciously set fires in residential areas near the Lualualei Naval Magazine and the Makua Military Reservation on Oahu could easily spread to threaten a nearby population of S. nuttallii.

Erosion, landslides, and rockslides due to natural weathering are particular threats on Oahu to the Pa-hole-Makua Ridge population of S. nuttallii.

Conservation and Recovery

The U.S. Army Garrison's five-year Ecosystem Management Plans to protect endangered species, prevent range fires, and minimize soil erosion are expected to enhance conservation of the S. nuttallii plants found on the army's Makua Military Reservation. The 28 plants of this species found on the army's Makua Military Reservation are currently within a fenced enclosure.

A long-range management plan for Honouliuli Preserve also includes actions for alien plant management, ungulate control, fire control, rare species recovery, and native habitat restoration. It is expected that these actions will benefit any plants of S. nuttallii still extant within the Preserve. S. nuttallii has been successfully propagated at Lyon Arboretum, the National Tropical Botanical Gardens and the State's Pahole Plant Nursery. More than 5,000 seeds were in storage in 1997 at the National Tropical Botanical Gardens.

The black twig borer has been identified as an important threat of S. nuttallii in the Makua Military Reservation. Plants there suffer slight to severe defoliation and reduced vigor to infestations of this alien insect. Research is needed to develop methods to control the borer; similarly, research is needed to determine how to prevent alien slugs and snails from eating seedlings of this species.

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
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 10 October 1996. "De-termination of Endangered or Threatened Status for Fourteen Plant Taxa From the Hawaiian Islands." Federal Register 61 (168): 53108-53124.