North America Native Plant

Hanapepe River Colicwood

Botanical name: Myrsine mezii

USDA symbol: MYME2

Life cycle: perennial

Habit: tree

Native status: Native to Hawaii  

Hanapepe River Colicwood: Hawaii’s Rarest Tree You Shouldn’t Plant in Your Garden Meet the Hanapepe River colicwood (Myrsine mezii), one of Hawaii’s most endangered native trees and quite possibly a plant you’ve never heard of – and for good reason. This critically imperiled species is so rare that you’re more ...

Rare plant alert!

Region: United States

Status: S1: Status is uncertain but is somewhere between the following rankings: 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) ⚘ Endangered: In danger of extinction throughout all or a significant portion of its range. ⚘

Region: United States

Hanapepe River Colicwood: Hawaii’s Rarest Tree You Shouldn’t Plant in Your Garden

Meet the Hanapepe River colicwood (Myrsine mezii), one of Hawaii’s most endangered native trees and quite possibly a plant you’ve never heard of – and for good reason. This critically imperiled species is so rare that you’re more likely to spot a Hawaiian monk seal sunbathing in your backyard than find this tree growing wild.

What Makes This Tree So Special (and So Rare)

The Hanapepe River colicwood is a perennial tree that belongs to the primrose family, though it looks nothing like the cheerful garden primroses you might know. This Hawaiian endemic typically grows as a single-trunked tree reaching heights of 13 to 16 feet or more, though environmental conditions can sometimes create shorter, multi-stemmed forms.

What makes this tree truly remarkable isn’t just its appearance – it’s its rarity. With a Global Conservation Status of S1, meaning Critically Imperiled, and listed as Endangered in the United States, this species is hanging on by a thread. Typically, this classification means there are five or fewer known occurrences or fewer than 1,000 individual plants remaining in the wild.

Where You’d Find It (If You Could Find It)

As its common name suggests, the Hanapepe River colicwood is native to Hawaii, specifically associated with the Hanapepe River area on the island of Kauai. This tree has evolved to thrive in Hawaii’s unique tropical conditions and is found nowhere else on Earth.

Why You Shouldn’t Plant This Tree (Even If You Could)

Here’s the thing about critically endangered plants – they’re not meant for your average garden, no matter how much you might want to help. Growing rare native species requires:

  • Specialized knowledge of their exact habitat requirements
  • Legitimate conservation partnerships
  • Responsibly sourced plant material (never collected from wild populations)
  • Proper permits and documentation

Attempting to grow this species without proper expertise and sourcing could actually harm conservation efforts rather than help them.

Growing Conditions (For Conservation Purposes Only)

If you’re involved in legitimate conservation efforts, the Hanapepe River colicwood requires tropical conditions similar to its native Hawaiian habitat. This means USDA hardiness zones 10-11, with warm temperatures year-round, high humidity, and specific soil and moisture requirements that mimic its natural Kauai environment.

How You Can Actually Help

Instead of trying to grow this rare tree yourself, here are meaningful ways to support its conservation:

  • Support Hawaiian native plant conservation organizations
  • Choose other native Hawaiian plants for your garden if you live in suitable zones
  • Learn about and spread awareness of Hawaii’s endangered flora
  • Visit botanical gardens and arboreta that participate in conservation programs

Better Alternatives for Your Garden

If you’re inspired by Hawaiian native plants but want something you can actually grow, consider these more available (though still special) options:

  • Other Myrsine species that aren’t endangered
  • Hawaiian native plants suited to your climate zone
  • Native plants from your own region that support local ecosystems

The Takeaway

The Hanapepe River colicwood represents something precious and irreplaceable – a unique piece of Hawaii’s natural heritage that’s barely surviving. While we can’t all have one in our backyards, we can appreciate its significance and support the dedicated scientists and conservationists working to ensure this remarkable tree doesn’t disappear forever. Sometimes the best way to love a plant is to admire it from afar and let the experts handle the growing.

Hanapepe River Colicwood

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Dilleniidae

Order

Primulales

Family

Myrsinaceae R. Br. - Myrsine family

Genus

Myrsine L. - colicwood

Species

Myrsine mezii Hosaka - Hanapepe River colicwood

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