No Common Name
|Listed||October 29, 1991|
|Description||Perennial with a short woody stem, elliptic leaves, and a scattered cluster of flowers with purple bracts and sepals.|
|Habitat||Steep slopes and shaded sites in moist forest.|
|Threats||Feral pigs and goats, alien plant species, fire, predation by alien slugs, low numbers.|
Schiedea kaalae is a perennial of the pink family with a short, woody stem less than 8 in (20 cm) long. Elliptic leaves, 9.5 in (24 cm) long, are bunched at the top of the stem. The petal-less flowers, carried on a branched stem 8-16 in (20-40 cm) long, have purple bracts and sepals. The fruits are capsules containing dark gray seeds. This plant has been observed in flower from March through June. Based on field and greenhouse observations, S. kaalae has perfect flowers.
A series of experimental self-pollinations, within-population crosses, and crosses among populations have demonstrated that S. kaalae experiences moderately strong inbreeding depression. These results indicate that reductions in population size could result in expression of inbreeding depression in seedlings, with potentially deleterious consequences for the long-term persistence of this species.
Consistent with the evidence for inbreeding depression, S. kaalae appears to be an outcrossing species. Under greenhouse conditions, flowers do not set fruit unless pollinated. In the field, this species was observed being visited by the introduced syrphid fly Simosyrphus grandicornis. The fly did not appear to be foraging for nectar but may have been feeding on pollen.
Individuals of species appear to be long-lived, but there is no evidence of regeneration from seed under field conditions. Seedlings of S. kaalae, like those of other Schiedea species in mesic or wet sites, are apparently consumed by introduced slugs and snails, which have been observed feeding on S. membranacea, a mesic forest species from the Hawaiian island of Kauai. Schiedea occurring in dry areas produce abundant seedlings following winter rains, presumably because dry areas have fewer alien consumers.
S. kaalae grows on steep slopes and shaded sites in moist forest at elevations of 700-2,600 ft (210-790 m). Associated plant species include kukui or candlenut (Aleurites moluccana ), Athyrium sandwicensis, Delissea subcordata, and papala kepau (Pisonia umbellifera ).
Historically, S. kaalae was known from the north-central and south-central Waianae Mountains and the northern Koolau Mountains on the Hawaiian island of Oahu. This species remains on state and private lands at Pahole Gulch, Kaluaa Gulch, Pohakea Pass, Puu Kaua, and Palawai Gulch in the Waianae Mountains and at Maalma Gulch and Makaua Stream in the Koolau Mountains. The five extant populations in the Waianae Mountains, distributed over an area of about 1 mi (1.6 km) by 10 mi (16 km), and the two current populations in the Koolau Mountains, just 4 mi (6.4 km) apart, contained only 13 plants in 1997.
The major threats to S. kaalae are habitat degradation by feral pigs and goats; competition from the alien plants Christmas berry, Maui pamakani, huehue haole, Koster's curse, molasses grass, and firetree; fire; predation by introduced slugs and snails; and the small number of extant individuals.
Conservation and Recovery
Fencing and removal of feral pigs in the Pahole drainage was completed by the State of Hawaii's Division of Forestry and Wildlife in July 1997. Weeding of strawberry guava, Christmas berry, and Koster's curse continues in the surrounding areas. The Nature Conservancy of Hawaii has plans to build a fenced exclosure in the Palawai area that should help to protect the individuals reported from this location.
One seed accession was completed in 1997 from the Kaawa site, and 130 S. kaalae individuals are now housed in the mid-elevation Nike site ready for out-planting at a still to be determined site. This species is also being successfully propagated at the National Tropical Botanical Garden, the Lyon Arboretum, and the Waimea Arboretum.
In addition to the work completed in Pahole Gulch, enclosures should be constructed around the other known populations of this plant to reduce impacts from feral ungulates. Subsequent control or removal of hoofed mammals from these areas will alleviate their impact on native ecosystems. Once these populations are enclosed, commitments should be developed for their long-term steward-ship and conservation.
Control of introduced snails and slugs is essential for protection of this species. This species reproduces prolifically under greenhouse conditions; therefore, the lack of seedlings in the field is almost certainly the consequence of grazing by alien snails and slugs. Evidence from other species of Schiedea that occur in mesic areas suggests that these snails and slugs consume seeds of all these species, as well as probably a substantial portion of the seed crop. Methods to control mollusk predation on seeds and seedlings of S. kaalae need to be found and implemented.
Research on pollinators is necessary because of the possibility that declines in native pollinator fauna might increase levels of inbreeding and result in the expression of inbreeding depression. Estimates on inbreeding depression for S. kaalae are not available.
A coordinated fire protection plan for endangered plant species on state (Pahole National Area Reserve) and private lands (Honolulu Preserve) needs to be developed and implemented.
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
U. S. Fish and Wildlife Service
Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-1201
Fax: (808) 541-1216
Cuddihy, L. W., and C. P. Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities, and Introductions. Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.
Stone, C. P., and J. M. Scott, eds. 1985. Hawai'i's Terrestrial Ecosystems: Preservation and Management Cooperative National Park Resources Study Unit, University of Hawaii Press, Honolulu.
Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1990. Manual of the Flowering Plants of Hawai'i. University of Hawaii Press and Bishop Museum Press, Honolulu.