North America Native Plant

Kauai Yellow Loosestrife

Botanical name: Lysimachia kalalauensis

USDA symbol: LYKA

Life cycle: perennial

Habit: shrub

Native status: Native to Hawaii  

Synonyms: Lysimachia hanapepeensis H. St. John (LYHA4)  âš˜  Lysimachiopsis helleri (R. Knuth) O. Deg. & I. Deg. (LYHE2)  âš˜  Lysimachia hillebrandii Hook. f. ex A. Gray var. helleri R. Knuth (LYHIH)   

Kauai Yellow Loosestrife: A Rare Hawaiian Treasure Worth Protecting If you’re drawn to unique Hawaiian native plants, you might have stumbled across the Kauai yellow loosestrife (Lysimachia kalalauensis). But before you start planning where to plant this beauty in your garden, there’s something important you need to know about this ...

Rare plant alert!

Region: Conservation status by state

Status: S2: Status is uncertain but is somewhere between the following rankings: Imperiled: Extremely rare due to factor(s) making it especially vulnerable to extinction. Typically 6 to 20 occurrences or few remaining individuals (1,000 to 3,000) ⚘

Kauai Yellow Loosestrife: A Rare Hawaiian Treasure Worth Protecting

If you’re drawn to unique Hawaiian native plants, you might have stumbled across the Kauai yellow loosestrife (Lysimachia kalalauensis). But before you start planning where to plant this beauty in your garden, there’s something important you need to know about this remarkable shrub.

A Plant on the Edge

The Kauai yellow loosestrife isn’t just rare—it’s imperiled. With a Global Conservation Status of S2, this native Hawaiian shrub has only 6 to 20 known occurrences remaining, with an estimated 1,000 to 3,000 individual plants left in the wild. That makes it one of Hawaii’s most vulnerable native species, teetering on the edge of extinction.

Where Does It Call Home?

This perennial shrub is found exclusively in Hawaii, specifically on the island of Kauai. It’s what botanists call an endemic species—meaning it exists nowhere else on Earth. The plant has quite a collection of scientific aliases too, having been known by names like Lysimachia hanapepeensis and Lysimachiopsis helleri throughout its taxonomic history.

What Does It Look Like?

As a multi-stemmed woody shrub, Kauai yellow loosestrife typically grows to less than 13-16 feet tall, with several stems emerging from or near the ground. Like many members of the loosestrife family, it’s a perennial that comes back year after year—assuming it has the right conditions to thrive.

Should You Grow Kauai Yellow Loosestrife?

Here’s where things get complicated. While supporting native Hawaiian plants is admirable, the extreme rarity of Kauai yellow loosestrife means this isn’t a plant for casual gardening. If you’re absolutely determined to grow this species, you must—and we can’t stress this enough—only source it through responsible conservation programs or certified native plant nurseries that work directly with conservation efforts.

The Responsible Alternative

Instead of potentially contributing to the decline of wild populations, consider these approaches:

  • Support conservation organizations working to protect this species in its natural habitat
  • Choose other native Hawaiian Lysimachia species that are less threatened
  • Focus on native Hawaiian plants that are more readily available and better suited for cultivation
  • Create habitat gardens that support the types of ecosystems where rare species like this one belong

Growing Conditions and Care

Due to its rarity, specific cultivation information for Kauai yellow loosestrife is limited. What we do know is that it’s adapted to Hawaii’s unique climate and ecosystem conditions. Like many Hawaiian natives, it likely prefers:

  • Consistent moisture without waterlogging
  • Protection from strong winds
  • Hawaii’s naturally warm, humid conditions
  • Well-draining soil that mimics its native forest habitat

The Bigger Picture

The story of Kauai yellow loosestrife is really a story about conservation. Every rare plant represents thousands of years of evolution and adaptation to specific environmental conditions. When we lose these species, we lose irreplaceable pieces of Hawaii’s natural heritage.

Rather than trying to grow this imperiled species in your garden, consider becoming an advocate for Hawaiian native plant conservation. Support local botanical gardens, conservation organizations, and research efforts that work to protect and restore populations of rare species like the Kauai yellow loosestrife.

The Bottom Line

While the Kauai yellow loosestrife is undoubtedly a fascinating and important native Hawaiian plant, its imperiled status means it’s not appropriate for home cultivation. The best way to appreciate and support this rare shrub is to protect its remaining wild populations and choose more sustainable native alternatives for your garden. Sometimes, the most loving thing we can do for a plant is to admire it from a respectful distance and work to ensure it survives for future generations to appreciate.

Kauai Yellow Loosestrife

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

Primulaceae Batsch - Primrose family

Genus

Lysimachia L. - yellow loosestrife

Species

Lysimachia kalalauensis Skottsb. - Kauai yellow loosestrife

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