North America Non-native Plant

Blechnum Underwoodianum

Botanical name: Blechnum underwoodianum

USDA symbol: BLUN2

Native status: Not native but doesn't reproduce and persist in the wild

Synonyms: Struthiopteris underwoodiana Broadh. (STUN3)   

Blechnum underwoodianum: The Mystery Fern That’s Hard to Pin Down If you’ve stumbled across the name Blechnum underwoodianum in your plant research, you’re not alone in scratching your head. This particular fern species is something of an enigma in the botanical world, with limited documentation and unclear classification that makes ...

Blechnum underwoodianum: The Mystery Fern That’s Hard to Pin Down

If you’ve stumbled across the name Blechnum underwoodianum in your plant research, you’re not alone in scratching your head. This particular fern species is something of an enigma in the botanical world, with limited documentation and unclear classification that makes it a puzzle even for experienced gardeners and botanists.

What We Know (And Don’t Know) About This Fern

Blechnum underwoodianum belongs to the Blechnum genus, commonly known as chain ferns or hard ferns. These are typically robust, evergreen ferns known for their distinctive chain-like arrangement of spore cases (sori) along the fronds. However, when it comes to this specific species, reliable information is surprisingly scarce.

The plant has a synonym – Struthiopteris underwoodiana – which suggests some historical taxonomic shuffling. This kind of name change often happens when botanists discover that a plant has been misclassified or when they gain new insights into plant relationships through modern research techniques.

The Challenge of Identification

Here’s where things get tricky for gardeners. Without clear documentation of this species’ characteristics, native range, or growing requirements, it’s nearly impossible to provide reliable identification tips or growing advice. This is frustrating if you’re trying to identify a fern in your garden or considering adding one to your landscape.

What This Means for Your Garden

If you encounter a plant labeled as Blechnum underwoodianum, approach with healthy skepticism. It’s possible that:

  • The plant is mislabeled and is actually a different, well-documented Blechnum species
  • The name represents an outdated classification that has since been updated
  • It’s a regional common name that doesn’t correspond to current botanical standards

Better Alternatives: Well-Known Chain Ferns

Instead of chasing this botanical ghost, consider these well-documented Blechnum species that make excellent garden additions:

  • Blechnum spicant (Deer Fern) – Great for shaded, moist areas in cooler climates
  • Blechnum brasiliense (Brazilian Tree Fern) – Striking architectural form for warmer regions
  • Blechnum gibbum (Miniature Tree Fern) – Perfect for containers and smaller spaces

The Bottom Line

While the mystery of Blechnum underwoodianum might intrigue plant enthusiasts, the lack of reliable information makes it impractical for garden planning. Your time and garden space are better invested in well-documented native ferns or established Blechnum species with known growing requirements and ecological benefits.

If you believe you’ve encountered this species in the wild or in cultivation, consider reaching out to local botanical experts or herbarium collections. You might be contributing to important botanical research – or helping solve a taxonomic puzzle that’s been sitting on the shelf for decades.

Blechnum Underwoodianum

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 underwoodianum (Broadh.) C. Chr. [excluded]

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