North America Native Plant

Kauai Pteralyxia

Botanical name: Pteralyxia kauaiensis

USDA symbol: PTKA

Life cycle: perennial

Habit: tree

Native status: Native to Hawaii  

Kauai Pteralyxia: A Critically Endangered Hawaiian Native Worth Protecting If you’re passionate about native Hawaiian plants and conservation, you’ve probably never heard of the Kauai pteralyxia (Pteralyxia kauaiensis) – and that’s precisely the problem. This remarkable native Hawaiian tree is so rare that it teeters on the edge of extinction, ...

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

Kauai Pteralyxia: A Critically Endangered Hawaiian Native Worth Protecting

If you’re passionate about native Hawaiian plants and conservation, you’ve probably never heard of the Kauai pteralyxia (Pteralyxia kauaiensis) – and that’s precisely the problem. This remarkable native Hawaiian tree is so rare that it teeters on the edge of extinction, making it one of the most critically imperiled plants in the Hawaiian Islands.

What Makes Kauai Pteralyxia Special?

The Kauai pteralyxia is a perennial tree that typically grows as a single-trunked woody plant, reaching heights of 13 to 16 feet or more under ideal conditions. What makes this species truly special isn’t just its rarity – it’s a living piece of Hawaiian natural heritage that has adapted specifically to the unique ecosystems of Kauai.

This tree produces small, fragrant white flowers and features simple, leathery leaves that help it thrive in Hawaii’s variable climate conditions. As a member of Hawaii’s native flora, it plays an important ecological role in supporting local wildlife and maintaining the integrity of native forest ecosystems.

Where Does It Grow?

Pteralyxia kauaiensis is found exclusively in Hawaii, specifically endemic to the island of Kauai. This tree naturally occurs in mesic to wet forest environments, where it has evolved to thrive in the island’s unique growing conditions.

The Conservation Reality: Why This Tree Needs Our Help

Here’s the sobering truth: Kauai pteralyxia has a Global Conservation Status of S1, meaning it’s critically imperiled. With typically five or fewer occurrences and very few remaining individuals (fewer than 1,000), this species is classified as Endangered in the United States. This isn’t just another rare plant – it’s a species hanging on by a thread.

Should You Plant Kauai Pteralyxia?

The short answer is: only if you can source it responsibly and you’re committed to conservation efforts. Due to its critically endangered status, this isn’t a plant for casual gardening. However, if you’re serious about Hawaiian native plant conservation and can obtain seeds or plants through legitimate conservation programs, botanical gardens, or certified native plant sources, growing Kauai pteralyxia can be an important contribution to species preservation.

Growing Conditions and Care

If you’re fortunate enough to acquire responsibly sourced Kauai pteralyxia, here’s what this special tree needs to thrive:

  • Climate: USDA hardiness zones 10-12 only (tropical and subtropical climates)
  • Light: Partial shade to filtered sunlight, mimicking its natural forest habitat
  • Soil: Well-draining soil that retains some moisture, similar to forest floor conditions
  • Water: Consistent moisture without waterlogging – think mesic to wet forest conditions
  • Protection: Shield from strong winds and extreme weather conditions

Landscape Role and Garden Design

In the right setting, Kauai pteralyxia serves as a centerpiece for native Hawaiian gardens, botanical collections, or conservation landscapes. Its moderate size makes it suitable for medium-sized spaces, and its rarity makes it a conversation starter about Hawaiian conservation efforts.

This tree works best in:

  • Native Hawaiian plant gardens
  • Educational botanical displays
  • Conservation-focused landscapes
  • Specialized collections of endangered species

Supporting Pollinators and Wildlife

While specific wildlife benefits aren’t well-documented due to the species’ rarity, native Hawaiian trees like Pteralyxia kauaiensis typically support native insects and contribute to the overall health of Hawaiian ecosystems. The fragrant flowers likely attract native Hawaiian pollinators, making each tree a small but important habitat island.

The Bottom Line

Kauai pteralyxia represents both a gardening challenge and a conservation opportunity. This isn’t a plant for everyone – it requires specific growing conditions, careful sourcing, and a commitment to conservation principles. But for dedicated native plant enthusiasts with the right conditions and ethical sources, growing this critically endangered tree can be a meaningful way to participate in preserving Hawaii’s irreplaceable natural heritage.

If you can’t grow Kauai pteralyxia yourself, consider supporting Hawaiian botanical gardens, conservation organizations, or native plant societies that work to protect species like this one. Sometimes the best way to help a rare plant is to ensure others can continue the vital work of keeping it alive for future generations.

Kauai Pteralyxia

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Gentianales

Family

Apocynaceae Juss. - Dogbane family

Genus

Pteralyxia K. Schum. - pteralyxia

Species

Pteralyxia kauaiensis Caum - Kauai pteralyxia

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