North America Native Plant

Royal Twinsorus Fern

Botanical name: Diplazium centripetale

USDA symbol: DICE

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Royal Twinsorus Fern: A Rare Puerto Rican Wetland Beauty Meet the royal twinsorus fern (Diplazium centripetale), a fascinating native fern that calls the tropical wetlands of Puerto Rico home. While you might not find this beauty at your local garden center, understanding this unique species gives us insight into the ...

Royal Twinsorus Fern: A Rare Puerto Rican Wetland Beauty

Meet the royal twinsorus fern (Diplazium centripetale), a fascinating native fern that calls the tropical wetlands of Puerto Rico home. While you might not find this beauty at your local garden center, understanding this unique species gives us insight into the incredible diversity of ferns that thrive in Caribbean ecosystems.

What Makes This Fern Special?

The royal twinsorus fern is a perennial fern species that’s perfectly adapted to life in wet, tropical conditions. As its classification suggests, this isn’t your typical backyard fern – it’s specifically evolved to thrive in obligate wetland conditions, meaning it almost exclusively lives in areas that stay consistently moist or wet year-round.

Where Does It Call Home?

This fern is endemic to Puerto Rico, making it a true island native. You’ll find it naturally growing in the island’s wetland areas, where it plays an important role in the local ecosystem. Its limited geographic range makes it quite special – and quite rare outside of its native habitat.

Should You Try Growing It?

Here’s where things get a bit tricky. The royal twinsorus fern presents some unique challenges for home gardeners:

  • Availability: This fern is extremely difficult to source commercially
  • Specialized needs: It requires very specific wetland conditions that are hard to replicate
  • Climate requirements: It’s adapted to tropical Puerto Rican conditions
  • Conservation concerns: Its limited range means we should be cautious about collection from wild populations

What Type of Garden Would Suit This Fern?

If you were able to obtain this fern through responsible sources, it would be perfect for:

  • Tropical wetland gardens
  • Bog gardens or rain gardens in warm climates
  • Conservation collections
  • Educational botanical displays

Growing Conditions (If You’re Lucky Enough to Find One)

Based on its natural habitat, the royal twinsorus fern would need:

  • Moisture: Consistently wet to boggy soil conditions
  • Climate: Warm, tropical temperatures year-round
  • Humidity: High humidity levels
  • Light: Likely prefers filtered light or partial shade

Better Alternatives for Your Garden

Since the royal twinsorus fern isn’t readily available and has very specific needs, consider these wetland-loving fern alternatives that are easier to grow:

  • Royal fern (Osmunda regalis) for temperate wetland gardens
  • Cinnamon fern (Osmundastrum cinnamomeum) for moist woodland areas
  • Sensitive fern (Onoclea sensibilis) for wet areas in cooler climates

The Bottom Line

While the royal twinsorus fern is a fascinating piece of Puerto Rico’s natural heritage, it’s more of a botanical curiosity than a practical garden plant for most of us. Its story reminds us of the incredible diversity of ferns in tropical ecosystems and the importance of protecting these specialized habitats. If you’re passionate about wetland gardening, focus on locally appropriate native ferns that will thrive in your specific climate and conditions – your garden (and local ecosystem) will thank you for it!

Wetland Status

The rule of seasoned gardeners and landscapers is to choose the "right plant for the right place" matching plants to their ideal growing conditions, so they'll thrive with less work and fewer inputs. But the simplicity of this catchphrase conceals how tricky plant selection is. While tags list watering requirements, there's more to the story.

Knowing a plant's wetland status can simplify the process by revealing the interaction between plants, water, and soil. Surprisingly, many popular landscape plants are wetland species! And what may be a wetland plant in one area, in another it might thrive in drier conditions. Also, it helps you make smarter gardening choices and grow healthy plants with less care and feeding, saving you time, frustration, and money while producing an attractive garden with greater ecological benefits.

Regions
Status
Moisture Conditions

Caribbean

OBL

Obligate Wetland - Plants with this status almost always occurs in wetlands

Royal Twinsorus Fern

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Dryopteridaceae Herter - Wood Fern family

Genus

Diplazium Sw. - twinsorus fern

Species

Diplazium centripetale (Baker) Maxon - royal twinsorus fern

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