Ha'iwale (Cyrtandra dentata)
|Listed||October 10, 1996|
|Family||Gesneriaceae (African violet)|
|Description||Branched shrub with papery textured leaves and three to nine white flowers.|
|Habitat||Gulches, slopes, or ravines in mesic forest with 'ohi'a, 'ohi'a ha, and kukui.|
|Threats||Competition from alien plants, potential predation by rats, and potential fire.|
Cyrtandra dentata, a member of the African violet family (Gesneriaceae), is a sparingly branched shrub ranging from 5-16 ft (1.5-4.9 m) in height. The papery leaves, 3.5-13 in (8.9-33.0 cm) long and 1.2-6.7 in (3.0-17.0 cm) wide, can be broadly elliptic to almost circular or broadly egg-shaped to egg-shaped. Three to nine white flowers are arranged on an inverse umbrella-shaped flower cluster that arises from the leaf axil. The main flower stalk is 1-2 in (2.5-5.0 cm) long; individual flower stalks are 0.6-1.3 in (1.5-3.3 cm) long; leaf-like bracts are 0.5-1.2 in (1.3-3.0 cm) long. The tubular portion of the flower is 0.5-1 in (1.3-2.5 cm) long and 0.2-0.4 in (5.1-10.2 mm) in diameter. The upper flower lobes are 0.08-0.2 in (2.0-5.0 mm) long and 0.1-0.3 in (2.5-7.6 mm) wide, while the lower lobes are 0.1-0.7 in (2.5-17.8 mm) long and 0.2-0.4 in (5.1-10.2 mm) wide. The round white berries are 0.4-1 in (1.0 2.5 cm) long. The number and arrangement of the flowers distinguish this species from others in the genus. Also distinguishing this species are the length of the bracts and flower stalks, and the shape of the leaves. This species has been observed in flower and fruit in May and November.
Harold St. John collected a plant specimen on Oahu in 1945 that he and W. B. Storey named C. dentata five years later. St. John and Storey, in the same paper, also described Cyrtandra frederickii, now considered synonymous with C. dentata. The specific epithet refers to the toothed margin of the leaf blades.
C. dentata typically grows in gulches, slopes, or ravines in mesic forest with 'ohi'a, 'ohi'a ha, and kukui at elevations from 1,900-2,360 ft (579-719 m).
C. dentata was known historically from six populations in the Waianae Mountains and three populations in the Koolau Mountains of Oahu. This species is currently found only in the Waianae Mountains at Pahole Gulch and Kapuna Valley on state land within Pahole Natural Area Reserves, on Army land at Makua Military Reservation in Kahanahaiki Gulch, and in Ekahanui Gulch on state and private land within the nature conservancy of Hawaii's Honouliuli Preserve. The number of individuals in the four known populations is not well documented, but the Kahanahaiki population in 1997 was approximately 50 individuals, while the total population probably numbered fewer than 70 plants.
Competition with the alien plants, Koster's curse and strawberry guava, potential predation by rats, potential fire, and a risk of extinction from naturally occurring events or through reduced reproductive vigor due to small and isolated populations are the major threats to C. dentata.
It is possible that rats eat the fruit of C. dentata, a plant with fleshy stems and fruit that grows in areas where rats occur.
The dense stands formed by strawberry guava threaten C. dentata, as does the noxious shrub Koster's curse.
Fire is also a potential threat to this species, which occurs in dry or mesic habitats where seasonal conditions exist for the easy spread of fire.
Conservation and Recovery
The Division of Forestry and Wildlife in July 1997 completed fencing and removal of feral pigs in the Pahole drainage. Weeding of strawberry guava, Christmasberry, and Koster's curse continues in the surrounding areas. This species is also being propagated at the Lyon Arboretum.
The army has adopted a fire management plan that includes realigning targets and establishing firebreaks at Makua Military Reservation. These actions may aid in protecting the two individuals at Kahanahaiki Gulch from the threat of fire. These two plants are currently within a large fenced enclosure from which ungulates have been eradicated.
Specific efforts should be made to immediately weed and protect all four populations.
All four C. dentata populations are potentially threatened by rat predation. A management plan to control rats should be developed and implemented. This should include the use of the currently approved diphacinone bait blocks and ultimately a more broad-scale method such as aerial dispersal of rodenticide.
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
Senior Resident Agent Office
U.S. Fish and Wildlife Service
300 Ala Moana Boulevard, Room 7-235
P.O. Box 50223
Honolulu, Hawaii 96850-5000
Telephone: (808) 541-2681
Fax: (808) 541-3062
U.S. Fish and Wildlife Service. 1998. "Recovery Plan for Oahu Plants." U.S. Fish and Wildlife Service, Portland.