'Oha (Delissea undulata)
|Listed||October 10, 1996|
|Description||Unbranched, palm-like, woody-stemmed tree, 6-32 ft (1.8-9.8 m) tall.|
|Habitat||Dry and mesic forests.|
|Threats||Degradation of habitat by feral animals.|
This 'oha, Delissea undulata, is an unbranched, palm-like, woody-stemmed tree, 6-32 ft (1.8-9.8 m) tall. A dense cluster of leaves occurs at the stem tip. Leaf blades are elliptic to narrowly lance-shaped, 2-8 in (5.1-20.3 cm) long, and 1-4 in (2.5-10.2 cm) wide. Leaf edges are wavy or flat and toothed. Leaf stalks are 0.8-5.9 in (2-15 cm) long. Flower clusters are subtended by a main stalk 2-20 in (5-50 cm) long. Each cluster is composed of about five to 20 flowers. The calyx and petals are fused at the base to form an oval tube 1.2-2.7 in (3-6.9 cm) long. Calyx lobes are awl-or triangular-shaped 0.04-0.08 in (0.1-2 mm) long. Petals are green-white and slightly down-curved, 0.6-1 in (1.5-2.5 cm) long. One or two knoblike structures often occur on the back of the flower tube. Fruits are oval or round, purple berries 0.2-0.48 in (.5-1.2 cm) long.
This taxon is distinguished from the other closely related members of the genus by its large flowers and berries and broad leaf bases. Three sub-species, all but the last of which are considered extinct, may be separated on the basis of leaf shape and margin characters: D. undulata var. Kauaiensis (leaf blades are oval and flat-margined with sharp teeth), D. undulata var. Niihauensis (leaf blades are heart shaped and flat-margined with shallow, rounded teeth) and D. undulata var. undulata (leaf blades are elliptic to lance-shaped and wavy-margined with small, sharply pointed teeth.
The remaining wild individual was observed in flower and (immature) fruit in August 1992, and outplanted individuals were observed in flower in July 1995. No other life history information is available.
D. undulata occurs in dry and mesic forests at elevations of about 3,300-5,700 ft (1,005.8-1,737.4 m) in open Sophora chrysophylla (mamane) and Metrosiderospolymorpha (ohia) forest. Taxa that are associated with D. undulata also include Santalurn ellipticum gaud. (iliahi) and Acacia koa (koa). Another endangered taxon, Nothocestrum brevifiorum, grows in the area where the single individual was found in 1992.
D. undulata spp. undulata was observed in the late nineteenth century on southwestern Maui in four valleys and in the early twentieth century on western Hawaii in North and South Kona. It was observed in South Kona at Puu Lehua in 1971, but was later thought to be extirpated. In 1992 a single individual was rediscovered at Puu Waawaa at the edge of a collapsed lava tube in a thin substrate at an elevation of 3,250 ft (990.6 m). Since then, about 50 individuals have been outplanted within three enclosures at Puu Waawaa, Waihou Forest Reserve.
Damage from feral and domestic animals and the degradation from grazing, browsing, and trampling by cows, sheep, goats, and pigs are threats. Although palatability of the taxon is not documented, lack of seedling establishment and low numbers of individuals suggest that the taxon may be negatively impacted by these animals. Three alien plant taxa pose a threat to D. undulata. Two vines—Passifiora mollissima and Senecio mikanioides Otto ex Walp. (German ivy)—and a noxious grass—Pennisetum clandestinurn (kikuyu grass)—compete with D. undulata for light, nutrients, and space and therefore limit or preclude reproductive success. Fire is potentially a threat, although fuel loads from Pennisetum clandestinum are minimized by heavy grazing by cattle. Predation of the fleshy fruits by black rats and introduced game birds is a threat to D. undulata. Because only one remaining wild adult plant known, D. undulata is threatened by extinction due to random events. For instance, natural changes to the habitat may threaten the preservation of this individual as it grows in a collapsing lava tube. Obviously a limited gene pool exists.
Conservation and Recovery
Seeds were obtained from the Puu Waawaa plant and germinated. Approximately 50 individuals were outplanted within three exclosures at Puu Waawaa, Waihou Forest Reserve.
The propagation and maintenance of ex situ genetic stock for this taxon is necessary in order to protect it from the serious threat of extinction by random event. Protection and outplanting efforts should be encouraged and continued.
U. S. Fish and Wildlife Service
Regional Office of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
U. S. Fish and Wildlife Service. 1996. Big Island Plant Cluster Recovery Plan. U. S. Fish and Wildlife Service, Portland, Oregon.