North America Non-native Plant

Potamogeton ×pusilliformis

Botanical name: Potamogeton ×pusilliformis

USDA symbol: POPU21

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

Synonyms: Potamogeton ×intermedius Fisch. (POIN32)   

Potamogeton ×pusilliformis: The Mystery Pondweed Hybrid Meet Potamogeton ×pusilliformis, one of those botanical puzzles that keeps plant enthusiasts scratching their heads. This aquatic plant is a hybrid pondweed that exists somewhere in the murky waters between well-documented species and botanical mystery. If you’re the type of gardener who likes a ...

Potamogeton ×pusilliformis: The Mystery Pondweed Hybrid

Meet Potamogeton ×pusilliformis, one of those botanical puzzles that keeps plant enthusiasts scratching their heads. This aquatic plant is a hybrid pondweed that exists somewhere in the murky waters between well-documented species and botanical mystery. If you’re the type of gardener who likes a challenge—or simply has a thing for unusual aquatic plants—this one might intrigue you.

What Exactly Is This Plant?

Potamogeton ×pusilliformis belongs to the pondweed family, a group of aquatic plants that spend their lives submerged or floating in freshwater environments. The × in its name tells us it’s a hybrid, meaning it’s the offspring of two different Potamogeton species that decided to get together and create something new. It’s also known by the synonym Potamogeton ×intermedius, which gives you a hint that even botanists have had some confusion about exactly what to call this plant.

The Challenge of Growing the Unknown

Here’s where things get interesting (and slightly frustrating): there’s remarkably little information available about this specific hybrid’s characteristics, native range, or growing requirements. This presents both an opportunity and a challenge for adventurous water gardeners.

Geographic Distribution and Native Status

The geographic distribution and native status of Potamogeton ×pusilliformis remain unclear from available sources. This uncertainty makes it difficult to determine whether this hybrid occurs naturally in North American waters or has been introduced from elsewhere.

Should You Plant It?

Given the limited information available about this hybrid, most gardeners would be better served choosing well-documented native pondweeds for their water features. Here’s why:

  • Uncertain growing requirements make success unpredictable
  • Unknown ecological impact in your local ecosystem
  • Difficulty obtaining from reputable sources
  • Limited guidance available for care and maintenance

Better Alternatives for Your Water Garden

Instead of taking a gamble on this mysterious hybrid, consider these well-documented native pondweed options:

  • Potamogeton natans (Floating-leaf Pondweed) – excellent for wildlife
  • Potamogeton illinoensis (Illinois Pondweed) – great for fish habitat
  • Potamogeton crispus (though this one can be aggressive, so research first)

If You’re Determined to Try It

Should you somehow encounter Potamogeton ×pusilliformis and decide to give it a go, treat it like other pondweeds:

  • Plant in calm, freshwater environments
  • Provide muddy or sandy substrate
  • Ensure good water quality
  • Monitor closely for any aggressive spreading
  • Be prepared to remove it if it doesn’t behave well with other plants

The Bottom Line

Potamogeton ×pusilliformis represents one of those botanical curiosities that’s more interesting in theory than in practice for most gardeners. While there’s something appealing about growing a plant that’s essentially a living mystery, the lack of reliable information makes it a risky choice for water gardens. Your pond—and the local ecosystem—will likely be happier with a well-researched native alternative that you can grow with confidence.

Sometimes the most responsible gardening choice is admitting when we simply don’t know enough about a plant to recommend it. This mysterious pondweed hybrid falls squarely into that category.

Potamogeton ×pusilliformis

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Alismatidae

Order

Najadales

Family

Potamogetonaceae Bercht. & J. Presl - Pondweed family

Genus

Potamogeton L. - pondweed

Species

Potamogeton ×pusilliformis Fisch. [excluded]

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