North America Native Plant

Rockbank Midsorus Fern

Botanical name: Blechnum lineatum

USDA symbol: BLLI

Life cycle: perennial

Habit: forb

Native status: Native to Puerto Rico  

Synonyms: Struthiopteris lineata (Sw.) Broadh. (STLI5)   

Rockbank Midsorus Fern: A Native Puerto Rican Beauty for Your Shade Garden If you’re looking to add some tropical flair to your shade garden, the rockbank midsorus fern (Blechnum lineatum) might just be the perfect addition. This charming native Puerto Rican fern brings a touch of the Caribbean rainforest right ...

Rockbank Midsorus Fern: A Native Puerto Rican Beauty for Your Shade Garden

If you’re looking to add some tropical flair to your shade garden, the rockbank midsorus fern (Blechnum lineatum) might just be the perfect addition. This charming native Puerto Rican fern brings a touch of the Caribbean rainforest right to your backyard – assuming you live somewhere warm enough to keep it happy!

What Makes the Rockbank Midsorus Fern Special?

The rockbank midsorus fern is a perennial fern that’s perfectly at home in Puerto Rico’s lush landscapes. You might also see it listed under its scientific synonym, Struthiopteris lineata, but don’t let that confuse you – it’s the same delightful plant. This native beauty has earned its place in the hearts of tropical gardeners who appreciate plants that truly belong in their local ecosystem.

Where Does It Call Home?

This fern is native to Puerto Rico, where it thrives in the island’s diverse microclimates. As a true Puerto Rican native, it’s perfectly adapted to the local conditions and plays an important role in the island’s natural plant communities.

Why Consider This Fern for Your Garden?

There are several compelling reasons to welcome the rockbank midsorus fern into your landscape:

  • Native plant benefits: If you’re gardening in Puerto Rico, you’re supporting local ecosystems by choosing native species
  • Wetland flexibility: This adaptable fern can handle both wetland and non-wetland conditions, making it versatile for various garden situations
  • Perennial reliability: Once established, this perennial will return year after year
  • Low-maintenance appeal: Native plants typically require less fussing once they’re settled in

Perfect Garden Settings

The rockbank midsorus fern shines in:

  • Tropical shade gardens
  • Woodland or forest-style landscapes
  • Native plant gardens
  • Areas with dappled sunlight
  • Naturalized garden settings

Growing Conditions and Care

Like most tropical ferns, the rockbank midsorus fern prefers:

  • Light: Partial to full shade – think dappled sunlight filtering through trees
  • Soil: Moist, well-draining soil rich in organic matter
  • Climate: USDA hardiness zones 10-11 (this is definitely a warm-weather plant!)
  • Humidity: High humidity levels, typical of tropical environments

Planting and Care Tips

Getting your rockbank midsorus fern established is fairly straightforward:

  • Choose a shaded spot protected from harsh direct sunlight
  • Prepare the soil with plenty of organic compost or leaf mold
  • Keep soil consistently moist but not waterlogged
  • Mulch around the base to retain moisture and suppress weeds
  • In very dry periods, provide supplemental watering

A Note for Mainland Gardeners

While this fern is a fantastic choice for Puerto Rican gardens, mainland gardeners in zones 10-11 should consider whether there are more locally appropriate native fern species for their specific region. Supporting your local native plant community is always the best ecological choice!

The Bottom Line

The rockbank midsorus fern is a wonderful choice for tropical gardeners, especially those in Puerto Rico who want to celebrate their local flora. It’s adaptable, attractive, and requires minimal fuss once established. Just remember – this is definitely a warm-weather plant, so make sure your climate can accommodate its tropical preferences before you fall in love with this charming Caribbean native.

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

Rockbank Midsorus Fern

Classification

Group

Fern

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision
Division

Pteridophyta - Ferns

Subdivision
Class

Filicopsida

Subclass
Order

Polypodiales

Family

Blechnaceae Newman - Chain Fern family

Genus

Blechnum L. - midsorus fern

Species

Blechnum lineatum (Sw.) C. Chr. - rockbank midsorus fern

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