North America Native Plant

Singlelobe Twinsorus Fern

Botanical name: Diplazium unilobum

USDA symbol: DIUN4

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Discovering the Singlelobe Twinsorus Fern: A Rare Puerto Rican Native Meet the singlelobe twinsorus fern (Diplazium unilobum), a fascinating native fern that calls the beautiful island of Puerto Rico home. While this perennial fern might not be as well-known as some of its flashier flowering cousins, it represents an important ...

Discovering the Singlelobe Twinsorus Fern: A Rare Puerto Rican Native

Meet the singlelobe twinsorus fern (Diplazium unilobum), a fascinating native fern that calls the beautiful island of Puerto Rico home. While this perennial fern might not be as well-known as some of its flashier flowering cousins, it represents an important piece of Puerto Rico’s unique botanical heritage.

What Makes This Fern Special?

The singlelobe twinsorus fern belongs to the diverse Diplazium genus, a group of ferns known for their distinctive spore-bearing structures. As its name suggests, this species has a characteristic single-lobed appearance that sets it apart from other ferns in its family. Like all ferns, it’s a non-flowering vascular plant that reproduces through spores rather than seeds.

Classified as a forb, this fern lacks the woody tissue you’d find in shrubs or trees. Instead, it maintains its perennial nature through underground structures that allow it to return year after year, making it a reliable presence in its native habitat.

Where You’ll Find It

This endemic beauty is found exclusively in Puerto Rico, where it has adapted to the island’s unique climate and growing conditions. Its limited geographic distribution makes it a true treasure of Caribbean biodiversity.

Garden Benefits and Identification

While detailed growing information for this specific species is limited, ferns like the singlelobe twinsorus fern can offer several benefits to gardens:

  • Natural air purification and humidity regulation
  • Attractive, lush green foliage that adds texture to shaded areas
  • Low-maintenance ground cover option for appropriate climates
  • Support for native ecosystem biodiversity

Growing Considerations

Based on its wetland status as a Facultative Upland plant, the singlelobe twinsorus fern typically prefers non-wetland conditions but can adapt to occasionally moist environments. This flexibility suggests it might be suitable for gardens with varying moisture levels.

As a Puerto Rican native, this fern would likely thrive in warm, humid conditions similar to its natural habitat. However, due to limited cultivation information and its restricted native range, sourcing this particular species for home gardens may be challenging.

Conservation Considerations

Given its limited distribution to Puerto Rico only, the singlelobe twinsorus fern represents an important part of the island’s endemic flora. While its conservation status isn’t well-documented in available sources, any endemic species with such a restricted range deserves our attention and respect.

If you’re interested in growing native Puerto Rican ferns, consider working with local native plant societies or botanical gardens to learn about available species and responsible sourcing practices.

The Bottom Line

The singlelobe twinsorus fern may be a botanical mystery in many ways, but that’s precisely what makes it intriguing. As gardeners increasingly recognize the importance of native plants, species like this remind us that there’s still so much to discover and protect in our natural world.

While you might not find this particular fern at your local nursery, learning about it helps us appreciate the incredible diversity of plant life that exists in places like Puerto Rico. And who knows? Maybe increased interest in native ferns will lead to better cultivation information and availability in the future.

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

FACU

Facultative Upland - Plants with this status usually occurs in non-wetlands but may occur in wetlands

Singlelobe 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 unilobum (Poir.) Hieron. - singlelobe 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