North America Native Plant

Riedel’s Twinsorus Fern

Botanical name: Diplazium riedelianum

USDA symbol: DIRI2

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Synonyms: Diplazium verapax (J. Sm.) Hieron. (DIVE4)   

Riedel’s Twinsorus Fern: A Puerto Rican Native Worth Knowing Meet Riedel’s twinsorus fern (Diplazium riedelianum), a charming native fern that calls Puerto Rico home. While this perennial beauty might not be the most well-known member of the fern family, it has its own quiet appeal for gardeners interested in native ...

Riedel’s Twinsorus Fern: A Puerto Rican Native Worth Knowing

Meet Riedel’s twinsorus fern (Diplazium riedelianum), a charming native fern that calls Puerto Rico home. While this perennial beauty might not be the most well-known member of the fern family, it has its own quiet appeal for gardeners interested in native Caribbean flora.

What Exactly Is Riedel’s Twinsorus Fern?

Diplazium riedelianum is a perennial fern that belongs to the diverse world of non-flowering vascular plants. Unlike the woody shrubs and trees in your garden, this fern is technically classified as a forb – meaning it lacks significant woody tissue above ground. Think of it as nature’s delicate, green carpet that comes back year after year without the fuss of woody growth.

You might occasionally see this fern listed under its synonym, Diplazium verapax, but don’t let that confuse you – it’s the same lovely plant.

Where Does This Fern Call Home?

This fern is exclusively native to Puerto Rico, making it a true island endemic. If you’re gardening anywhere in Puerto Rico, you’re working with a plant that has naturally evolved in your local ecosystem – which is always a gardening win!

Is It Good for Your Garden?

Here’s where things get interesting. Riedel’s twinsorus fern has a facultative wetland status, which is a fancy way of saying it’s flexible about where it grows. This adaptable nature means it can handle both wetland conditions and drier spots – making it potentially useful for:

  • Transition zones between wet and dry areas in your landscape
  • Areas with variable moisture levels
  • Natural, low-maintenance garden designs

What About Wildlife Benefits?

While we don’t have specific data on wildlife interactions with this particular fern, most native ferns provide some ecological benefits. They won’t attract pollinators like flowering plants do (since ferns don’t flower), but they often serve as:

  • Shelter for small wildlife and beneficial insects
  • Part of the natural food web in forest ecosystems
  • Erosion control with their root systems

Growing Challenges and Considerations

Here’s the honest truth about Riedel’s twinsorus fern – it’s not the easiest plant to find information about, and that might extend to finding the plant itself. As a Puerto Rico endemic, it’s likely best suited for:

  • Gardeners specifically in Puerto Rico
  • Those creating authentic Caribbean native plant gardens
  • Naturalistic landscapes that mimic local forest conditions

Given its facultative wetland status, it probably appreciates consistent moisture without being waterlogged, and like most ferns, it likely prefers some shade to partial shade conditions.

Should You Plant It?

If you’re gardening in Puerto Rico and can source this fern responsibly from native plant nurseries, it could be a wonderful addition to a native plant collection. Its adaptability to various moisture conditions makes it potentially valuable for challenging spots in your landscape.

However, if you’re outside Puerto Rico, this probably isn’t the fern for you – and that’s okay! There are likely wonderful native fern species in your area that will be much easier to find, grow, and maintain.

The Bottom Line

Riedel’s twinsorus fern represents the quiet beauty of Puerto Rico’s native flora. While it might not be a showstopper or the easiest plant to track down, it embodies the charm of gardening with plants that truly belong in your local ecosystem. For Puerto Rican gardeners interested in authentic native landscaping, it’s definitely worth seeking out from reputable native plant sources.

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

FAC

Facultative - Plants with this status can occur in wetlands and non-wetlands

Riedel’s 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 riedelianum (Bong. ex Kunze) C. Presl - Riedel's 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