North America Native Plant

Gray’s Bur Cucumber

Botanical name: Sicyos cucumerinus

USDA symbol: SICU3

Life cycle: annual

Habit: vine

Native status: Native to Hawaii  

Gray’s Bur Cucumber: A Rare Hawaiian Treasure Worth Protecting If you’re a native plant enthusiast with a passion for conservation, you might have come across the intriguingly named Gray’s bur cucumber (Sicyos cucumerinus). This little-known Hawaiian native deserves our attention—not necessarily for your backyard garden, but for its critical conservation ...

Rare plant alert!

Region: Conservation status by state

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) ⚘

Gray’s Bur Cucumber: A Rare Hawaiian Treasure Worth Protecting

If you’re a native plant enthusiast with a passion for conservation, you might have come across the intriguingly named Gray’s bur cucumber (Sicyos cucumerinus). This little-known Hawaiian native deserves our attention—not necessarily for your backyard garden, but for its critical conservation status and unique place in Hawaii’s natural heritage.

What Makes Gray’s Bur Cucumber Special?

Gray’s bur cucumber is a climbing annual herb that belongs to the cucumber family, though you won’t be adding its fruits to your salad anytime soon. This delicate vine produces small white flowers and distinctive spiny fruits that give it the bur part of its common name. As a forb (a non-woody flowering plant), it lacks the thick, woody stems you’d find on shrubs or trees, instead growing as a tender herbaceous vine.

A Hawaiian Endemic in Crisis

Here’s where things get serious: Gray’s bur cucumber is found nowhere else on Earth except Hawaii, and it’s currently classified as S1—Critically Imperiled. This sobering designation means there are typically five or fewer known populations, with fewer than 1,000 individual plants remaining in the wild.

This rare native is endemic to the Hawaiian Islands, where it once played its part in the complex web of native ecosystems that evolved in isolation over millions of years.

Should You Grow Gray’s Bur Cucumber?

The short answer: Only if you’re involved in legitimate conservation efforts.

Given its critically imperiled status, Gray’s bur cucumber isn’t something you should casually add to your garden wishlist. If you’re interested in growing this species, you must ensure any plant material comes from responsible, ethical sources—ideally conservation organizations or botanical gardens working to preserve Hawaiian native species.

Growing Conditions and Care

For those involved in conservation efforts, here’s what Gray’s bur cucumber needs to thrive:

  • Climate: Tropical conditions (USDA zones 10-12)
  • Light: Partial shade, mimicking its natural forest understory habitat
  • Soil: Well-draining but consistently moist soil
  • Support: Climbing structure, as this is a vining plant
  • Water: Regular moisture without waterlogging

Conservation Over Cultivation

Rather than focusing on how to grow Gray’s bur cucumber in your garden, let’s talk about how you can support its survival:

  • Support organizations working to protect Hawaiian native plants
  • Learn about and grow other Hawaiian natives that are less endangered
  • Spread awareness about Hawaii’s unique and threatened flora
  • If visiting Hawaii, respect natural areas where rare plants might be growing

The Bigger Picture

Gray’s bur cucumber represents the fragility of island ecosystems and the urgent need for native plant conservation. While we may not all be able to grow this rare species, we can appreciate its uniqueness and work to ensure that future generations will know more than just its name.

Every critically imperiled plant like Gray’s bur cucumber tells a story of ecosystem change, habitat loss, and the delicate balance of nature. By understanding and respecting these rare species, we become better stewards of all the native plants in our own regions.

Sometimes the most important thing we can do for a plant isn’t to grow it, but to protect the wild spaces where it belongs.

Gray’s Bur Cucumber

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

Violales

Family

Cucurbitaceae Juss. - Cucumber family

Genus

Sicyos L. - bur cucumber

Species

Sicyos cucumerinus A. Gray - Gray's bur cucumber

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