North America Native Plant

Hillebrand’s Phyllostegia

Botanical name: Phyllostegia hillebrandii

USDA symbol: PHHI4

Life cycle: perennial

Habit: vine

Native status: Native to Hawaii  

Hillebrand’s Phyllostegia: A Hawaiian Native on the Brink of Extinction If you’re passionate about native Hawaiian plants, you’ve probably never heard of Hillebrand’s phyllostegia (Phyllostegia hillebrandii) – and sadly, that might be because this remarkable native herb is possibly extinct in the wild. This perennial member of the mint family ...

Rare plant alert!

Region: Conservation status by state

Status: SH: Status is uncertain but is somewhere between the following rankings: Possibly Extinct: Known only from historical occurrences. Still some hope of rediscovery ⚘

Hillebrand’s Phyllostegia: A Hawaiian Native on the Brink of Extinction

If you’re passionate about native Hawaiian plants, you’ve probably never heard of Hillebrand’s phyllostegia (Phyllostegia hillebrandii) – and sadly, that might be because this remarkable native herb is possibly extinct in the wild. This perennial member of the mint family represents one of Hawaii’s most critically endangered plant species, serving as a sobering reminder of what we stand to lose when native ecosystems disappear.

What Makes This Plant Special

Phyllostegia hillebrandii belongs to a fascinating genus of Hawaiian mints found nowhere else on Earth. As a native forb herb, this perennial plant lacks the woody stems of shrubs and trees, instead producing soft, herbaceous growth that emerges from buds at or below ground level each growing season. Like other members of the mint family, it likely produced small, tubular flowers that would have been perfectly adapted to Hawaii’s native pollinators.

Where It Once Called Home

This endemic species was historically found only in Hawaii, making it a true treasure of the Hawaiian Islands’ unique flora. Historical records suggest it grew in the understory of native Hawaiian forests, thriving in the islands’ mesic to wet forest ecosystems.

A Conservation Crisis

Here’s where the story takes a heartbreaking turn. Phyllostegia hillebrandii currently holds a Global Conservation Status of SH, which means Possibly Extirpated. In plain terms, this plant is known only from historical records, and botanists haven’t confirmed any living populations in recent years. While there’s still some hope that hidden populations might exist in remote forest areas, the outlook is grim.

Should You Try to Grow It?

The short answer is: probably not, unless you’re involved in legitimate conservation efforts. Given its possible extinction status, any surviving genetic material is incredibly precious and should only be handled by qualified conservation botanists and authorized institutions. If you’re interested in supporting this species, consider:

  • Supporting Hawaiian native plant conservation organizations
  • Volunteering with forest restoration projects
  • Choosing other native Hawaiian plants for your garden
  • Advocating for habitat protection in Hawaii

Better Alternatives for Your Hawaiian Native Garden

While you shouldn’t attempt to grow Phyllostegia hillebrandii, Hawaii offers many other stunning native plants that you can cultivate responsibly. Consider these alternatives that share similar growing preferences:

  • Other Phyllostegia species that are less endangered
  • Native Hawaiian mints like Stenogyne species
  • Hawaiian native ferns for forest understory conditions
  • Indigenous flowering herbs adapted to your specific island and elevation

Growing Conditions It Would Need

If this species were available for cultivation, it would require very specific Hawaiian forest conditions. Based on its historical habitat, it would need:

  • Partial to full shade (forest understory conditions)
  • High humidity and consistent moisture
  • Well-draining but moisture-retentive soil
  • Protection from strong winds
  • USDA hardiness zones 10-12

The Bigger Picture

Phyllostegia hillebrandii’s story is unfortunately common among Hawaiian native plants. Habitat destruction, invasive species, and climate change have pushed many endemic species to the brink of extinction. As gardeners, we can make a difference by choosing native plants, supporting conservation efforts, and spreading awareness about these irreplaceable species.

While we may have lost Hillebrand’s phyllostegia, we can still work to protect the native plants that remain. Every native plant we grow, every invasive species we remove, and every dollar we donate to conservation makes a difference in preserving Hawaii’s unique botanical heritage for future generations.

Hillebrand’s Phyllostegia

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

Lamiales

Family

Lamiaceae Martinov - Mint family

Genus

Phyllostegia Benth. - phyllostegia

Species

Phyllostegia hillebrandii H. Mann ex Hillebr. - Hillebrand's phyllostegia

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