Platanthera holochila

No Common Name

Description

Platanthera holochila is an erect, deciduous herb of the orchid family (Orchidaceae). The stems arise from underground tubers and are 6-24 in (15-61 cm) long. The pale-green leaves, generally 2-5 in (5-12.5 cm) long and 0.4-1 in (1-2.5 cm) wide, are lance-to egg-shaped. The greenish-yellow flowers occur in open spikes. The back sepal is inversely egg-shaped and hooded; the lateral sepals are erect and elliptic. The lateral petals, which are 1 in (2.5 cm) long, are irregularly egg-shaped and enclosed by the sepals. The straplike lowest petal is about 0.1 in (2.5 mm) long, and the spur at its base is 0.1-0.2 in (2.5-5 mm) long. The fruit is an ellipsoid capsule with six ribs. This is the only species of this genus that occurs in the Hawaiian Islands.

The species was described and named Habenaria holochila in 1888 based on collections and on material sent by J. M. Lydgate and V. Knudsen. F. W. Kraenzlin subsequently transferred the species to the genus Platanthera, resulting in the new combination P. holochila, and this name is accepted in the current treatment of Hawaiian members of the family. C. A. Luer published the combination P. hyperborea var. viridiflora in 1975, now considered synonymous with P. holochila. The specific epithet refers to the undivided lip of the flower.

Habitat

P. holochila is found in 'ohi'a-Dicranopteris linearis (uluhe) montane wet forest or 'ohi'a mixed montane bog at elevations of 3,450-6,120 ft (1,050-1,865 m). Associated plant species include Cibotium sp. (hapu'u), Coprosma ernodeoides (kukaenene), Oreobolus sp., Styphelia sp. (pukiawe), and Vaccinium spp. ('ohelo).

Distribution

P. holochila was known historically from the Alakai Swamp and Kaholuamano area and the Wahiawa Mountains on Kauai, the Koolau Mountains on Oahu, scattered locations on Molokai, and various locations on Maui.

P. holochila is currently known from five locations on Kauai, Molokai, and Maui. Before the devastation of Hurricane 'Iniki, on Kauai in September 1992, two populations were known on state land from the Alakai Swamp within the Alakai Wilderness Preserve. One population, last seen in 1977, was not observed when the location was revisited in 1989. The other population comprised 100 plantlets representing three clones, but this occurrence was reduced more than a year after Hurricane 'Iniki to only 10 immature plantlets representing one clone. On Molokai, a single population of less than 10 plants occurs on private land in the Nature Conservancy's Kamakou Preserve. The three populations known on Maui are from Hanaula, on state and private land, and the Nature Conservancy's Waikamoi and Kapunakea Preserves. The five current populations comprised less than 41 individuals in 1997—one plant occurred on Kauai, 20 on Molokai, and 15-20 on Maui.

Threats

Habitat degradation by feral pigs and a risk of extinction from naturally occurring events and reduced reproductive vigor due to the small number of existing populations are the major threats to P. holochila. The Kaukonahua-Kahana Divide population on Oahu is additionally threatened by competition with an alien plant and potential harm from military activities.

Feral pigs threaten one population of P. holochila on Oahu and the Eke Crater population on Maui.

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

Collecting for scientific or horticultural purposes and visits by individuals avid to see rare plants are potential threats to P. holochila, whose few populations are well-known and close to trails or roads. One P. holochila individual died in the late 1980s after a portion of the plant was collected for scientific purposes.

Narrow-leaved carpet grass is a threat to one population of P. holochila on Oahu.

Conservation and Recovery

In February and March of 1997, under the auspices of a genetic material collection project funded by the U. S. Fish and Wildlife Service, botanists set out to collect propagation material of P. holochila from the Kauai and Hanaula, Maui, populations. All plants were dormant, however, and the plants at Kamakou Preserve on Kauai appeared feeble and very yellow, so the botanists decided against taking cuttings. The plants at Hanaula were fenced in 1995 by the Nature Conservancy; in 1997, the Kauai plant was also protected by fencing.

Micropropagation of P. holochila is being attempted at Lyon Arboretum, although successful results have not yet been attained.

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. "Determination of Endangered or Threatened Status for 14 Plant Taxa from the Hawaiian Islands." Federal Register 61 (198): 53108-53124.