Growing Kawa’u: Hawaii’s Rare Native Citrus Relative
Meet kawa’u (Zanthoxylum dipetalum var. dipetalum), one of Hawaii’s most intriguing native trees and a lesser-known member of the citrus family. This perennial woody plant might not be as famous as its mainland cousins, but it holds a special place in Hawaii’s unique botanical heritage.
What Makes Kawa’u Special?
Kawa’u is a true Hawaiian endemic, meaning it evolved naturally in the islands and exists nowhere else on Earth. This remarkable tree typically grows as a single-stemmed specimen reaching heights of 13-16 feet or more, though environmental conditions can sometimes create shorter, multi-stemmed forms.
As a member of the Zanthoxylum genus, kawa’u shares DNA with prickly ash and other aromatic trees known for their distinctive thorny bark and compound leaves. The small flowers may seem modest, but they play an important role in supporting Hawaii’s native pollinators.
Where Does Kawa’u Grow?
This native treasure is found exclusively in Hawaii, where it has adapted to the islands’ unique climate and growing conditions over thousands of years.
Important Conservation Considerations
Here’s something every potential grower needs to know: kawa’u has a Global Conservation Status of S2T2, indicating it’s quite rare in the wild. This means if you’re considering adding this special tree to your garden, you should only obtain plants from reputable native plant nurseries or conservation programs that use responsibly sourced, legally propagated material.
Never collect plants or seeds from wild populations – this can harm already vulnerable native ecosystems.
Is Kawa’u Right for Your Garden?
Kawa’u works best in specific garden settings:
- Native Hawaiian plant gardens and landscapes
- Restoration projects focusing on endemic species
- Botanical collections celebrating Hawaii’s unique flora
- Educational gardens showcasing rare native plants
This tree serves as an excellent specimen plant, providing structure and height while supporting local pollinators with its flowers. It’s particularly meaningful for gardeners passionate about preserving Hawaii’s natural heritage.
Growing Conditions and Care
Kawa’u thrives in USDA hardiness zones 10-11, making it suitable only for tropical and subtropical climates similar to its native Hawaiian environment. The tree prefers:
- Well-draining soils
- Partial to full sun exposure
- Moderate water requirements
- Protection from strong winds
Planting and Care Tips
Successfully growing kawa’u requires attention to its tropical needs:
- Ensure your climate stays consistently warm year-round
- Plant in a location with good drainage to prevent root rot
- Provide some wind protection, especially for young trees
- Minimal pruning is typically needed – let the tree develop its natural form
- Water regularly during establishment, then adjust based on rainfall
Supporting Conservation Through Gardening
By choosing to grow kawa’u responsibly, you’re participating in an important conservation effort. Home gardens can serve as genetic reservoirs for rare native plants, helping ensure these species survive for future generations.
Just remember: always source your plants ethically, never harvest from wild populations, and consider sharing seeds or cuttings with other conservation-minded gardeners to help expand this rare tree’s cultivated population.
Whether you’re creating a native Hawaiian landscape or simply want to grow something truly unique, kawa’u offers the chance to cultivate a piece of Hawaii’s irreplaceable natural heritage right in your own backyard.
