North America Native Plant

Niihau Delissea

Botanical name: Delissea niihauensis niihauensis

USDA symbol: DENIN

Life cycle: perennial

Habit: tree

Native status: Native to Hawaii  

Synonyms: Delissea undulata Gaudich. ssp. niihauensis (H. St. John) Lammers (DEUNN)   

Niihau Delissea: A Critically Rare Hawaiian Native Worth Protecting Meet the Niihau delissea (Delissea niihauensis niihauensis), one of Hawaii’s most precious and endangered native trees. This remarkable member of the bellflower family represents both the incredible biodiversity of the Hawaiian Islands and the urgent need for plant conservation. What Makes ...

Rare plant alert!

Region: Conservation status by state

Status: S1TH: 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) ⚘

Niihau Delissea: A Critically Rare Hawaiian Native Worth Protecting

Meet the Niihau delissea (Delissea niihauensis niihauensis), one of Hawaii’s most precious and endangered native trees. This remarkable member of the bellflower family represents both the incredible biodiversity of the Hawaiian Islands and the urgent need for plant conservation.

What Makes Niihau Delissea Special

The Niihau delissea is a perennial tree that can grow over 13-16 feet tall under ideal conditions, though environmental factors may sometimes result in shorter, multi-stemmed growth forms. As a member of the bellflower family, it produces distinctive tubular flowers and has characteristic lobed leaves that set it apart from other Hawaiian natives.

This tree is also known by its botanical synonym Delissea undulata Gaudich. ssp. niihauensis, reflecting its close relationship to other Delissea species found throughout Hawaii.

Where It Calls Home

The Niihau delissea is endemic to Hawaii, with its range historically centered on Niihau Island – hence its common name. This native Hawaiian species grows exclusively in Hawaii and represents part of the unique flora that evolved in isolation over millions of years.

A Plant in Crisis

Important Conservation Alert: The Niihau delissea has a Global Conservation Status of S1TH, indicating it is critically rare and faces significant threats. This means the species is extremely uncommon and potentially at risk of extinction.

If you’re interested in supporting Hawaiian native plants, we strongly recommend:

  • Only obtaining plants through reputable native plant societies or botanical gardens
  • Ensuring any plant material is responsibly sourced and legally obtained
  • Supporting conservation efforts for Hawaiian native plants
  • Considering more readily available Hawaiian native alternatives

Growing Conditions and Care

In its native habitat, Niihau delissea typically grows in dry to mesic (moderately moist) forest conditions. The species requires:

  • USDA hardiness zones 10-12 (tropical conditions)
  • Well-draining soils
  • Protection from strong winds
  • Specialized care from experienced native plant gardeners

Due to its rarity, this species is not suitable for casual gardening and requires expertise in Hawaiian native plant cultivation.

Supporting Pollinators and Wildlife

Like many Hawaiian native plants, the Niihau delissea likely evolved alongside native pollinators and may provide important resources for native Hawaiian birds and insects. However, with so few plants remaining, its current ecological role is limited.

Garden Alternatives

If you’re passionate about growing Hawaiian native plants, consider these more readily available alternatives that can provide similar benefits to your garden and local wildlife:

  • Other Delissea species that are less endangered
  • Native Hawaiian shrubs and trees from reputable native plant nurseries
  • Plants that support native Hawaiian pollinators and birds

How You Can Help

Rather than attempting to grow this critically rare species, consider supporting conservation efforts through donations to Hawaiian native plant organizations, volunteering for habitat restoration projects, or advocating for native plant protection. Every action helps ensure that future generations might once again see Niihau delissea thriving in Hawaiian forests.

The story of Niihau delissea reminds us that some plants are simply too precious and rare for home gardens – but that doesn’t make them any less worthy of our admiration and protection.

Niihau Delissea

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

Campanulales

Family

Campanulaceae Juss. - Bellflower family

Genus

Delissea Gaudich. - delissea

Species

Delissea niihauensis H. St. John - delissea

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