North America Native Plant

Royal Kihifern

Botanical name: Adenophorus tripinnatifidus

USDA symbol: ADTR2

Life cycle: perennial

Habit: forb

Native status: Native to Hawaii  

Royal Kihifern: Hawaii’s Delicate Native Epiphyte Meet the royal kihifern (Adenophorus tripinnatifidus), one of Hawaii’s most enchanting yet vulnerable native ferns. This delicate epiphytic beauty represents the incredible diversity of Hawaii’s endemic flora, but it’s also a plant that demands our respect and careful consideration before adding to any garden. ...

Rare plant alert!

Region: Conservation status by state

Status: S3: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘

Royal Kihifern: Hawaii’s Delicate Native Epiphyte

Meet the royal kihifern (Adenophorus tripinnatifidus), one of Hawaii’s most enchanting yet vulnerable native ferns. This delicate epiphytic beauty represents the incredible diversity of Hawaii’s endemic flora, but it’s also a plant that demands our respect and careful consideration before adding to any garden.

What Makes the Royal Kihifern Special?

The royal kihifern is a perennial fern that has evolved to live life in the trees. As an epiphyte, it doesn’t grow in soil like most plants we’re familiar with. Instead, it makes its home on the branches and trunks of other plants, drawing moisture and nutrients from the humid air around it. This fascinating lifestyle has shaped everything about how this fern looks and grows.

What sets this species apart is its incredibly fine, lacy foliage. The fronds are tripinnate, meaning they’re divided three times over, creating an almost feathery appearance that’s simply stunning when you encounter it in its natural habitat.

Where Does It Call Home?

The royal kihifern is found exclusively in Hawaii, making it a true endemic treasure of the islands. This fern grows naturally only in the Hawaiian archipelago, where it has adapted to the unique climate and growing conditions found nowhere else on Earth.

A Plant That Needs Our Protection

Here’s where things get serious: the royal kihifern has a Global Conservation Status of S3, meaning it’s considered vulnerable. With typically only 21 to 100 occurrences or between 3,000 and 10,000 individuals remaining, this isn’t a plant to take lightly. It’s rare and local throughout its range, which makes every individual precious.

If you’re considering adding this fern to your collection, please ensure you’re sourcing it responsibly from reputable native plant nurseries that propagate their own stock rather than collecting from wild populations. Never collect this fern from the wild – it needs every individual it can get to maintain healthy populations.

Is the Royal Kihifern Right for Your Garden?

Let’s be honest – this isn’t a beginner’s plant. The royal kihifern requires very specific growing conditions that can be challenging to replicate outside of its native Hawaiian environment. It thrives in USDA hardiness zones 10-12, which limits it to tropical and subtropical regions.

This fern is perfect for:

  • Tropical shade gardens with high humidity
  • Specialized epiphyte collections
  • Hawaiian native plant gardens
  • Greenhouse cultivation in cooler climates

Growing Conditions and Care

The royal kihifern demands high humidity, filtered light, and excellent air circulation. Since it’s an epiphyte, you’ll need to mount it on a suitable host tree or grow it in a specialized epiphytic growing medium rather than regular potting soil.

Key growing requirements include:

  • High humidity (60-80%)
  • Bright, filtered light (no direct sun)
  • Excellent air circulation
  • Consistent moisture without waterlogging
  • Warm temperatures year-round

Supporting Hawaiian Native Plants

While the royal kihifern might not provide direct benefits to pollinators like flowering plants do, it plays an important role in Hawaii’s native ecosystem. As part of the complex web of epiphytic plants that create mini-ecosystems in tree canopies, it contributes to the overall biodiversity that supports various wildlife species.

If you’re passionate about Hawaiian native plants but find the royal kihifern too challenging, consider other native Hawaiian ferns that might be easier to grow while still supporting conservation efforts. Every native plant we successfully cultivate helps preserve Hawaii’s unique botanical heritage.

Growing the royal kihifern is ultimately about more than just adding an exotic fern to your collection – it’s about participating in the conservation of Hawaii’s irreplaceable native flora. With patience, the right conditions, and responsibly sourced plants, you can help ensure this vulnerable species continues to grace Hawaiian forests for generations to come.

Royal Kihifern

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Grammitidaceae Newman - Kihi Fern family

Genus

Adenophorus Gaudich. - kihifern

Species

Adenophorus tripinnatifidus Gaudich. - royal kihifern

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