North America Native Plant

Kawa’u

Botanical name: Zanthoxylum dipetalum var. tomentosum

USDA symbol: ZADIT

Life cycle: perennial

Habit: tree

Native status: Native to Hawaii  

Kawa’u: Hawaii’s Rare Native Tree Worth Protecting Meet the kawa’u (Zanthoxylum dipetalum var. tomentosum), one of Hawaii’s most precious and endangered native trees. This remarkable perennial woody plant represents a true botanical treasure that deserves our attention and protection. A Tree on the Brink Before we dive into the world ...

Rare plant alert!

Region: United States

Status: S2T1: Status is uncertain but is somewhere between the following rankings: Subspecies or variety is critically Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 5 or fewer occurrences or very few remaining individuals (<1,000) ⚘ Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘ Endangered: In danger of extinction throughout all or a significant portion of its range. ⚘

Region: United States

Kawa’u: Hawaii’s Rare Native Tree Worth Protecting

Meet the kawa’u (Zanthoxylum dipetalum var. tomentosum), one of Hawaii’s most precious and endangered native trees. This remarkable perennial woody plant represents a true botanical treasure that deserves our attention and protection.

A Tree on the Brink

Before we dive into the world of kawa’u, there’s something important you need to know: this tree is extremely rare. With a Global Conservation Status of S2T1 and listed as Endangered in the United States, kawa’u is teetering on the edge of extinction. This means that while we absolutely want to celebrate and potentially grow this species, we must do so responsibly and only with properly sourced material from conservation programs or authorized nurseries.

Hawaii’s Native Heritage

Kawa’u is a plant species native exclusively to Hawaii, making it a true island endemic. This perennial tree grows naturally only in the Hawaiian Islands, where it has evolved over thousands of years to thrive in the unique island ecosystem.

What Makes Kawa’u Special

As a tree species, kawa’u is a woody perennial that typically grows with a single trunk and can reach heights greater than 13 to 16 feet under optimal conditions. However, like many Hawaiian natives, it may sometimes develop a multi-stemmed or shorter growth form depending on environmental conditions.

Growing Kawa’u: Proceed with Care

Given its endangered status, growing kawa’u comes with special responsibilities. Here’s what you need to know:

  • Source responsibly: Only obtain plants from authorized conservation programs, botanical gardens, or certified native plant nurseries
  • Climate needs: As a Hawaiian native, kawa’u thrives in tropical conditions similar to USDA zones 10-12
  • Conservation priority: Consider this more of a conservation effort than typical gardening
  • Expert guidance: Consult with local conservation groups or botanical experts before attempting to grow this species

A Garden with Purpose

If you’re fortunate enough to grow kawa’u, you’re not just adding a plant to your garden—you’re participating in conservation. This tree would be most appropriate in:

  • Conservation gardens focused on Hawaiian natives
  • Educational landscapes that highlight endangered species
  • Restoration projects in appropriate Hawaiian habitats
  • Specialized collections dedicated to rare native plants

The Bottom Line

Kawa’u represents both an incredible opportunity and a serious responsibility. While we don’t have extensive information about its specific growing requirements or garden performance due to its rarity, we do know it’s a precious piece of Hawaii’s natural heritage that needs our help to survive.

If you’re passionate about Hawaiian native plants and conservation, kawa’u might be worth pursuing—but only through proper channels and with a commitment to conservation. For most gardeners interested in Hawaiian natives, consider starting with more common native species while supporting conservation efforts for rare gems like kawa’u.

Remember, every plant grown responsibly is a step toward preventing extinction and preserving Hawaii’s unique botanical legacy for future generations.

Kawa’u

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Rosidae

Order

Sapindales

Family

Rutaceae Juss. - Rue family

Genus

Zanthoxylum L. - pricklyash

Species

Zanthoxylum dipetalum H. Mann - kawa'u

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA