North America Native Plant

Bladderfern

Botanical name: Cystopteris ×illinoensis

USDA symbol: CYIL

Life cycle: perennial

Habit: forb

Native status: Native to the lower 48 states  

The Elusive Illinois Bladder Fern: A Rare Native Hybrid Worth Knowing Meet Cystopteris ×illinoensis, a fascinating native fern that’s more elusive than a perfect parking spot at the garden center. This perennial beauty, commonly known as the Illinois bladder fern, represents one of nature’s botanical mysteries – a natural hybrid ...

The Elusive Illinois Bladder Fern: A Rare Native Hybrid Worth Knowing

Meet Cystopteris ×illinoensis, a fascinating native fern that’s more elusive than a perfect parking spot at the garden center. This perennial beauty, commonly known as the Illinois bladder fern, represents one of nature’s botanical mysteries – a natural hybrid that calls just a few Midwestern states home.

What Makes This Fern Special?

The × in its scientific name isn’t a typo – it’s botanical shorthand telling us this is a hybrid species. Think of it as nature’s own plant breeding experiment, created when two different bladder fern species decided to collaborate. The result is a delicate, lacy fern with the characteristic thin, papery fronds that give bladder ferns their common name.

Where You’ll Find This Native Gem

This rare fern has a surprisingly small neighborhood – it’s only been documented in Illinois, Ohio, and Wisconsin. That’s a pretty exclusive zip code for a native plant! Its limited range makes it a true regional specialty of the Great Lakes area.

A Word of Caution for Eager Gardeners

Here’s where we need to pump the brakes a bit. Due to its hybrid nature and extremely limited distribution, Cystopteris ×illinoensis is likely quite rare in the wild. If you’re lucky enough to encounter this fern, it’s best admired rather than collected. Responsible gardening means protecting rare species like this one.

Garden Alternatives That Won’t Keep You Up at Night

Instead of hunting for this rare hybrid, consider these more common native bladder ferns that offer similar beauty:

  • Common bladder fern (Cystopteris fragilis)
  • Bulblet bladder fern (Cystopteris bulbifera)
  • Other native woodland ferns suited to your region

If You’re Considering This Fern

Should you somehow find this species available through reputable native plant sources (and we mean really reputable), here’s what it would need:

  • Light: Partial to full shade – direct sun is not its friend
  • Soil: Moist, well-draining soil with good organic content
  • Hardiness: Likely hardy in USDA zones 4-7 based on its native range
  • Maintenance: Low-maintenance once established, typical of most native ferns

The Bottom Line

While Cystopteris ×illinoensis is undoubtedly a botanical treasure, it’s one best left to specialized botanical collections and research institutions. For most gardeners, focusing on more readily available native ferns will give you that same woodland magic without contributing to the pressure on rare species.

Remember, the best native gardening practices protect rare species while celebrating the abundance of beautiful, more common native plants that can thrive in our gardens. Your local native plant society can help you discover the perfect ferns for your specific location – ones that won’t require you to become a botanical detective to source responsibly!

Bladderfern

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

Cystopteris Bernh. - bladderfern

Species

Cystopteris ×illinoensis R.C. Moran [bulbifera × tenuis] - bladderfern

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