Pendant Kihi Fern

Adenophorus periens

Description

The pendant kihi fern (Adenophorus periens ), a member of the grammitis family, is a small, pendant, epiphytic fern. The rhizome is covered with dark and stiff scales 0.8-1.6 in (2-4.1 cm) long. Its yellowish-green fronds are usually 4-16 in (10.2-40.6 cm) long and covered with hairs. The fronds have slightly hairy stalks less than 0.4 in (1 cm) long. Each frond is comprised of oblong or narrowly triangular pinnae (divisions or leaflets) 0.2-0.6 in (5.1-15.2 mm) long with margins that are smooth or toothed and lined with sparse hairs. The pinnae are situated perpendicular to the axis of the midrib, with each pinna twisted such that its upper surface faces upward. Groups of spore-producing bodies called sori, in this case round, usually develop in the central portion of the fertile frond, forming two regular rows on each pinna. This species differs from other species in this endemic Hawaiian genus by (1) having hairs along the pinna margins, (2) having pinnae at right angles to the midrib axis, (3) the different placement of the sori, and (4) the degree of dissection of each pinna.

A. periens was first collected by Captain Fredrick William Beechey in the 1820s or 1830s. It was not formally described until 1974, when L. Earl Bishop published the name A. periens. Prior to its description, the names Polypodium adenophorus and A. pinnatifidus had been erroneously applied to the species represented by Beechey's specimen.

The breeding system of A. periens is unknown, although very likely outbreeding is the predominant mode of reproduction. Spores are dispersed by wind, possibly by water, and perhaps on the feet of birds or insects. Spores lack a thick resistant coat, which may indicate their longevity is brief, probably measured in days at most. Due to the weak differences between the seasons, there seems to be no evidence of seasonality in growth or reproduction. A. periens appears to be susceptible to volcanic emissions and consequent acid precipitation.

Habitat

A. periens is found in 'ohi'a/hapu'u lowland wet forest at elevations of 1,540-4,140 ft (469.4-1,261.9m). It is found in habitats of well-developed, closed canopy that provide deep shade and high humidity. Associated species include kanawao ke'oke'o, 'olapa, uluhe, 'ie'ie, and kopiko.

Distribution

A. periens was known historically from Hale-manu on Kauai, the Koolau Mountains of Oahu, the summit of Lanai, Kula Pipeline on East Maui, and Hilo and Waimea on the island of Hawaii. The species is now known from several locations on three islands. On Kauai, one population occurs at the boundary of Hono O Na Pali Natural Area Reserve and Na Pali Coast State Park on state land, one occurs at Waioli on state land, and four are clustered on private land in the Wahiawa area over a distance of 0.8 sq mi (2.1 sq km). There is a single Molokai population of three plants on private land at Kamakou Preserve. On the Big Island of Hawaii, four populations are found at Olaa Tract, Kane Nui o Hamo Crater, Kahaualea Natural Area Reserve, and 1.5 mi (2.4 km) northwest of Puu Kauka on private, state, and federal land. The status of the population at Kane Nui o Hamo is uncertain due to recent volcanic eruptions and drought. The 13-18 extant populations totaled approximately 1,295-1,330 individuals in 1997, of which 79-83 were on Kaui, six were on Molokai, and 1,215-1,241 were on Hawaii Island.

Threats

The primary threats to A. periens are (1) habitat degradation by pigs; (2) competition for light, space, nutrients, and water with alien plant species, among them strawberry guava, Koster's curse, yellow Himalayan raspberry, prickly Florida blackberry, and banana poke vine; and (3) habitat destruction by fires.

An A. periens population in Kahaualea Natural Area Reserve on the island of Hawaii is jeopardized by fire. Tephra fallout and lava flows from Kilauea Volcano have affected the Natural Area Reserve over the past several years. Wildfires ignited by volcanic activity have destroyed some of the reserve's mesic and wet forests. While 65,000-100,000 plants were reported from this area in 1988, no plants were found during a 1993 survey. These plants may have been killed by either sulphyr dioxide fumes from Puu Oo or by several periods of drought. Tephra fallout and noxious volcanic gasses have also caused extensive damage to surrounding native forests. Such catastrophic natural events threaten to destroy the region's largest population of A. periens.

Conservation and Recovery

Spores were collected in 1996 from an individual on Molokai for cultivated propagation at the University of Hawaii's Lyon Arboretum; however, germination was not successful. An unknown number of spores are in storage at the National Tropical Botanical Garden.

In order to reduce the risk of extirpation of populations of A. periens in volcanically active areas, a volcanic hazard contingency plan should be developed for these plants. During some future volcanic event it may be necessary to rescue these populations if habitat becomes threatened by fire, tephra fallout, or lava flows.

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
Telephone: (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. 10 November 1994. "Endangered Status for 12 Plants from the Hawaiian Islands." Federal Register 59 (217): 56333-56351.