CPC Plant Profile: Kawa`u
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Plant Profile

Kawa`u (Zanthoxylum dipetalum var. tomentosum)

A closeup view of new leaves of this species. Photo Credit: Peter Van Dyke
  • Global Rank: T1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Rutaceae
  • State: HI
  • Nature Serve ID: 133606
  • Date Inducted in National Collection: 03/05/1993

Zanthoxylum dipetalum is a tree that can grow up to 15 meters tall with a trunk that can grow as large as 30 cm in diameter. The yellowish wood of this species was used by early Hawaiians for tools as well as instruments used for long distance communication. There are two recognized varieties of Zanthoxylum dipetalum. The first, variety dipetalum, is found on four Hawaiian islands. The second, variety tomentosum, is rare and found only on the island of Hawai'i. This variety is distinguished from Zanthoxylum dipetalum var. dipetalum by the hairs on the undersurface of its leaflets. It is distinguished from other Hawaiian species of the genus by reduced lower leaflets, the presence of only one joint on some of the leaflet stalks, and larger seeds. (Wagner et al. 1999)

Participating Institutions
Nature Serve Biotics
  • 05/02/2017

Recorded only from Puuwaawaa in the district of North Kona, Hawaii Island. Fewer than 30 trees are known to remain. The taxon's habitat has been grazed for many decades, and now consists of scattered remant native trees in cattle pasture. Threats include cattle, pigs, alien plants, and fire.

Not Available
  • 01/01/2010

As stated by the U.S. Fish and Wildlife Service at the time of listing (USFWS 1996), threats include: Browsing by cattle, feral pigs and sheep Trampling by cattle, feral pigs and sheep Habitat disturbance by cattle, feral pigs and sheep Competitio

Not Available
  • 01/01/2010

Only one population has ever been known, discovered by J.F. Rock in 1919, it is located at Puu Waawaa on Hualalai, on the island of Hawaii. Approximately 24 individuals are now known, scattered through the area. (USFWS 1996)

Not Available
  • 01/01/2010

Arslanian et al. (1990) determined the biochemical constituents of this species' leaves.

Not Available
  • 01/01/2010

None known.

Not Available
  • 01/01/2010

Monitoring is necessary for basic information about this rare variety that can help direct any management efforts. The integrity of the natural system where the only known population is found should be maintained.

Not Available
  • 01/01/2010

Propagation and maintenance of ex situ plants is necessary. More research is needed on long term seed storage techniques.


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Taxon Zanthoxylum dipetalum var. tomentosum
Authority Rock
Family Rutaceae
CPC Number 13418
ITIS 530907
Common Names A'e | kawa'u
Associated Scientific Names Zanthoxylum dipetalum var. tomentosum
Distribution This species is located on Puu Waawaa on the volcano, Hualalai, on the island of Hawaii. (USFWS 1996)
State Rank
State State Rank
Hawaii S1

Degraded 'ohi'a-dominated montane mesic forests, often on aa lava, at elevations between 915 and 1040 meters. (USFWS 1996)Associated species include mamane, lama, 'ala'a, 'iliahi, 'ohe kolea, and kopiko. (USFWS 1996)

Ecological Relationships

A recently described rust is found only on a few trees of Zanthoxylum dipetalum var. dipetalum on the island of Kaua'i. (Gardner 1990)

Common Name Name in Text Association Type Source InteractionID

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