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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
Lifeform: Tree
Date Inducted in National Collection: 03/05/1993

Description:

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)

Where is Kawa`u (Zanthoxylum dipetalum var. tomentosum) located in the wild?

Habitat:

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)

Distribution:

This species is located on Puu Waawaa on the volcano, Hualalai, on the island of Hawaii. (USFWS 1996)

States & Provinces:

Kawa`u can be found in Hawaii

Which CPC Partners conserve Kawa`u (Zanthoxylum dipetalum var. tomentosum)?

Honolulu Botanical Gardens

Not Sponsored

Assigned 04/17/18

Harold L. Lyon Arboretum

Not Sponsored

Assigned 07/24/23

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

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.