North America Native Plant

Boyd’s Maiden Fern

Botanical name: Thelypteris boydiae

USDA symbol: THBO

Life cycle: perennial

Habit: forb

Native status: Native to Hawaii  

Synonyms: Christella boydiae (D.C. Eaton) Holttum (CHBO10)  âš˜  Cyclosorus boydiae (D.C. Eaton) W.H. Wagner (CYBO5)  âš˜  Cyclosorus boydiae (D.C. Eaton) W.H. Wagner var. kipahuluensis W.H. Wagner & A.C. Medeiros, nom. inq. (CYBOK)   

Boyd’s Maiden Fern: A Critically Endangered Hawaiian Treasure Meet Boyd’s maiden fern (Thelypteris boydiae), one of Hawaii’s rarest botanical treasures and a species that most gardeners will never encounter—and shouldn’t actively seek to grow. This isn’t your typical gardening advice, but sometimes the best thing we can do for a ...

Rare plant alert!

Region: United States

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) ⚘ Endangered: In danger of extinction throughout all or a significant portion of its range. ⚘

Region: United States

Boyd’s Maiden Fern: A Critically Endangered Hawaiian Treasure

Meet Boyd’s maiden fern (Thelypteris boydiae), one of Hawaii’s rarest botanical treasures and a species that most gardeners will never encounter—and shouldn’t actively seek to grow. This isn’t your typical gardening advice, but sometimes the best thing we can do for a plant is to admire it from afar and support conservation efforts instead.

What Makes This Fern So Special?

Boyd’s maiden fern is a perennial fern that belongs to the maiden fern family. As a true fern, it reproduces through spores rather than flowers and seeds, and it represents an ancient lineage of plants that have graced our planet for millions of years. This particular species is what botanists call a forb—essentially a non-woody vascular plant that lacks the thick, woody stems we see in trees and shrubs.

A Hawaiian Endemic in Crisis

This remarkable fern calls Hawaii home and is found nowhere else on Earth. It’s what we call an endemic species—a plant that evolved in isolation on the Hawaiian islands and exists nowhere else in the world.

But here’s where the story takes a sobering turn. Boyd’s maiden fern carries a Global Conservation Status of S1, which means it’s critically imperiled. In plain English, this fern is hanging on by a thread, with typically five or fewer known locations and fewer than 1,000 individual plants remaining in the wild. The U.S. government has listed it as Endangered, which should tell you just how precarious its situation really is.

Why You Shouldn’t Plant Boyd’s Maiden Fern

Now, you might be thinking, If it’s so rare, wouldn’t planting it help? While that instinct comes from a good place, there are several important reasons why home gardeners should steer clear:

  • Extremely limited availability: With so few plants left in the wild, any specimens in cultivation should be reserved for professional conservation programs
  • Unknown growing requirements: We simply don’t have enough information about this fern’s specific needs to grow it successfully
  • Conservation priority: Every effort and resource should go toward protecting existing wild populations
  • Potential harm: Amateur cultivation attempts could inadvertently contribute to the species’ decline

What We Do Know

Boyd’s maiden fern has a facultative wetland status in Hawaii, meaning it can survive in both wetland and non-wetland environments. This adaptability might seem like it would help the species survive, but clearly other factors are working against it.

The fern is also known by several scientific synonyms, including Christella boydiae and Cyclosorus boydiae, which you might encounter in older botanical literature or conservation documents.

How You Can Actually Help

Instead of trying to grow Boyd’s maiden fern, here are meaningful ways to support this species and Hawaiian native plants in general:

  • Support conservation organizations: Donate to or volunteer with groups working to protect Hawaiian native species
  • Choose other Hawaiian natives: Plant readily available Hawaiian native species that don’t face extinction
  • Spread awareness: Share information about endangered Hawaiian plants with other gardeners
  • Visit responsibly: If you’re in Hawaii, support eco-tourism that funds conservation efforts

The Bigger Picture

Boyd’s maiden fern serves as a powerful reminder of how fragile our native ecosystems can be. While we can’t all have this particular fern in our gardens, we can honor its existence by making thoughtful choices about the plants we do grow. Every time we choose a native plant over an exotic one, we’re making a small but meaningful contribution to biodiversity conservation.

Sometimes the most loving thing we can do for a plant is to let the experts handle its care while we focus on growing the many wonderful native species that aren’t teetering on the edge of extinction. Boyd’s maiden fern may be off-limits to home gardeners, but it can inspire us to be better stewards of the plants we can grow.

Boyd’s Maiden Fern

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Thelypteridaceae Ching ex Pic. Serm. - Marsh Fern family

Genus

Thelypteris Schmidel - maiden fern

Species

Thelypteris boydiae (D.C. Eaton) K. Iwats. - Boyd's maiden fern

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