CPC National Collection Plant Profile

Acacia koaia

Photographer:
K. Wood

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CPC National Collection Plant Profile

Acacia koaia


Family: 
Fabaceae  
Common Names: 
koai'a, koai'e, koa'oha
Author: 
Hillebr.
Growth Habit: 
Tree
CPC Number: 
17

Distribution
Protection
Conservation
References


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Acacia koaiaenlarge
Photographer: K. Wood
Image Owner: National Tropical Botanical Garden

Acacia koaiaenlarge
Photographer: D. Ragone
Image Owner: National Tropical Botanical Garden


Acacia koaia is Not Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 

 
Acacia koaia


Species that belong to the genus Acacia are member of the family Fabaceae, which is also commonly referred to as the legume, or pea, family. There are two Acacia species endemic to Hawai’i. The first, referred to as Acacia koa sensu stricto, is a fairly common Hawaiian tree that is well known for its decorative wood.

The other, A. koaia, is a rare tree that is adapted to drier conditions and has harder wood, a smaller stature, and more gnarled appearance than its more common relative. A. koaia can be locally abundant in drier habitats, but this habitat is seriously threatened (K. Wood pers. comm. 2002). This rare tree has sickle-shaped “leaves” that are actually phyllodes, or flat, expanded petioles that take the place leaf blades & perform the same functions. The flowers are formed in heads with cream-colored corollas, long, curled stamens (more than twice the length of the corolla) and pubescent ovaries. (Wagner et al. 1999)

To distinguish between the common and rare species, a number of characteristics can potentially be used. A. koaia pods are laterally flattened with longitudinally arranged seeds, narrower pods and straighter phyllodes than A. koa sensu stricto which has wider pods, laterally arranged seeds, and more curved phyllodes. A confounding problem has arisen because, on the northern coast of Kaua’i, a population of Acacia spp. has been found with the habit and phyllodes of A. koa sensu stricto but with the pods of A. koaia (Wagner et al. 1999).

Distribution & Occurrence

State Range
  Hawaii
State Range of  Acacia koaia
Habitat
  A. koaia is found in low elevations in drier, open woodland habitats (Wagner et al. 1999).

Associated species for A. koaia include Dicranopteris linearis (uluhe), Pandanus tectorius (hala), Bidens forbessii (no common name), Hibiscus kokio subsp. saintjohnianus (Koki’o ‘ula’ula), Lipochaeta connata var. acris (nehe), Pleomele aurea (Halapepe), and Metrosideros polymorpha (Ohia) (Wagner et al. 1990).

Distribution
  A. koaia is found on Kaua’i, O’ahu, Moloka’i, Lana’i, Maui and Hawai’i (USFWS 2001).

Number Left
  Number of populations: many (USFWS 2001)
Number of plants: >1000 (USFWS 2001)

Protection

Global Rank:  
G2
 
8/24/2000
Guide to Global Ranks
Federal Status:  
SC
 
4/11/2001
Guide to Federal Status
Recovery Plan:  
No
 

State/Area Protection
  State/Area Rank Status Date  
  Hawaii S2 4/11/2002  

Conservation, Ecology & Research

Ecological Relationships
  A. koaia is presumed to be insect-pollinated and its seeds are wind dispersed (Sakai et al. 1995).

Threats
  Threats to A. koaia include habitat degradation and herbivory by goats, and invasion of habitat by alien plant species. Because it occurs in low elevations, it has been severely impacted by historic ranching, agriculture and human-caused fires. (NatureServe 2001)

Current Research Summary
  Seeds of A. koaia have been tested by the National Seed Storage Laboratory (NSSL), finding that they are orthodox and tolerant to drying and freezing. The laboratory germination time was four months (Yoshinaga 2002).

Current Management Summary
  Judy and Will Hancock are assisting the Hawai'i Forest Stewardship Program (Kalopi Dryland Forest Restoration) in restoring the ridges of Kohala (Hawai’i). They have been planting A. koaia on the leeward side of the Kohala Mountains since 1989 and claim that the shorter A. koaia are better adapted to the windy, dry Kohala landscape. The goal of the Kalopi project is primarily to restore native Hawaiian dryland forest. However, any wood from harvest from dead or thinned trees is valued for its beautifully grained wood (Hawaii Forestry News 2000).

The National Tropical Botanical Garden (NTBG) currently has ex situ holdings of 204 seeds in its seed bank, which represents four populations. In addition, 100 individuals from four populations are growing in the botanical garden.

Research Management Needs
  1. Genetic studies are needed to confirm taxonomic and the phylogenetic status of A. koaia.
2. Genetic studies are also needed to confirm the distinctiveness between island populations.
3. Map genetic diversity in the surviving populations of A. koaia.
4. Test management strategies on invasive species and pest control for A. koaia.
Recommendations derived from M.H. Chapin, M. Maunder, and Wagner et al. (1999).

Ex Situ Needs
  1. Establish a full seed bank collection of A. koaia representing all available populations.
2. Development of proper horticultural protocols including pest management for A. koaia.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.

References

Books (Single Authors)

Bornhorst, H.L.; Rauch, F.D. 1994. Native Hawaiian Plants for Landscaping, Conservation, and Reforestation. Honolulu, HI: University of Hawaii--Hawaii Institute of Tropical Agriculture and Human Resources. 18p.

Sohmer, S.H.; Gustafson, R. 1987. Plants and Flowers of Hawaii. Honolulu, HI: University of Hawaii Press. 160p.

Wagner, W.L.; Bruegmann, M.M.; Herbst, D.R; Lau, J.Q.C. 1999. Hawaiian Vascular Plants at Risk: 1999. Honolulu, HI: Bishop Museum Press Honolulu.

Wagner, W.L.; Herbst, D.R. 2002. Supplement to the Manual of the Flowering Plants of Hawai'i. University of Hawaii Press.

Wagner, W.L.; Herbst, D.R.; Sohmer, S.H. 1999. Manual of the flowering plants of Hawai'i--Revised Edition. Honolulu, HI: University of Hawaii Press and Bishop Museum Press. 1853p.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Conference Proceedings

Anderson, R.C.; Gardner, D.E. Abstract: Investigations of koa (Acacia koa) decline in Hawaiian forests. The 1998 Hawai'i Conservation Conference; Honolulu, Hawai'i. 1998. Sponsored by the Secretariat for Conservation Biology.

Electronic Sources

NatureServe. (2008). NatureServe Explorer: An online encyclopedia of life [web application]. [Internet].Version 7.0. NatureServe, Arlington, Virginia. http://www.natureserve.org/explorer. Accessed: (June 17, 2008).

USFWS. (2001). Unpublished data. U.S. Fish and Wildlife Service, Honolulu, Hawaii 96817. Accessed: 2001.

Yoshinaga, A. (2002). Seed storage characteristics of Hawaiian species. [Web site] University of Hawaii, Honolulu, Hawaii 96848. http://www.hawaii.edu/scb/seed/seedtabl.html. Accessed: 2002.

Journal Articles

2000. Kalopi Dryland Forest Restoration. Renewable Resources Extension - Hawai‘i Forestry News. 3, 1: p. 6.

Hotchkiss, S.; Juvik, J. 1999. A Late-Quaternary pollen record from Kaëau Crater, O'ahu, Hawai'i. Quaternary Research. 52, 1: 1145-1208.

Larsen, M.; Lombard, F.F.; Hodges, C.S., Jr. 1985. Hawaiian USA forest fungi 5: a new species of phellinus hymenochaetaceae causing decay of casuarina and acacia. Mycologia. 77, 3: 345-352.

Niang, A.; Ugiziwe, J.; Styger, E.; Gahamanyi, A. 1996. Forage potential of eight woody species: Intake and growth rates of local young goats in the highland region of Rwanda. Agroforestry Systems. 34, 2: 171-178.

Sakai, A.K.; Wagner, W.L.; Ferguson, D.M.; Herbst, D.R. 1995. Origins of Dioecy in the Hawaiian Flora. Ecology. 76, 8: 2517-2529.

St. John, H. 1979. Classification of acacia-koa and relatives leguminosae Hawaiian plant studies 93. Pacific Science. 33, 4: 357-367.

USFWS. 1976. Proposed Endangered Status for 1700 U.S. Plants. Federal Register. 41: 24523-24572.

Reports

Leeper, J.R. 1973. The bioecology of Psylla uncatoides in the Hawaii Volcanoes National Park and the Acacia Koaia santuary. Island Ecosystems IRP, U.S. International Biological Program. p.13.


  This profile was updated on 9/28/2010
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