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Plant guide · Floating plants

Spatterdock (Nuphar lutea ssp. advena (Nuphar advena))

A native water lily relative with heart-shaped leaves and simple yellow flowers, rooted in the bottom with leaves that float or stand just above the water.

Also called: yellow pond-lily, cow lily

A round yellow spatterdock flower beside a large heart-shaped leaf, with duckweed on the water.
Spatterdock flower and leaf. Photo: Fritzflohrreynolds, CC BY-SA 3.0 (source)

What it looks like

  • Large heart-shaped leaves that float on the water or stand slightly above it.
  • Simple yellow flowers.
  • Rooted in the pond bottom, with stems reaching to the surface.

Easily confused with

  • White water lily: round leaves with a slit and white flowers.
  • Yellow floating heart (an invasive on Pennsylvania's noxious weed list): much smaller leaves than lilies.

Good and bad for your pond

  • A native plant that shades the water and shelters fish.
  • Can spread over shallow areas and crowd docks and launch spots.

Native or invasive?

Native

Native. Native (USDA PLANTS; Penn State lists spatterdock among native floating plants).

USDA PLANTS: NULUA (lower 48 states: native)

Do grass carp eat it?

Grass carp usually leave it alone

Grass carp usually don't control it. Grass carp prefer submerged plants like pondweeds, elodea and coontail; they rarely control algae mats or lilies.

Checked Oct 4, 2026 · Source: Using Grass Carp to Control Aquatic Plants (updated May 19, 2025) This may be outdated

Control options

Prevention first

Penn State Extension's advice for every nuisance plant and algae problem starts with nutrients: overgrowth is a symptom of excess phosphorus and nitrogen from sources such as barnyards, crop fields, septic systems, lawns and golf courses. Cutting fertilizer near the pond, maintaining septic systems, diverting nutrient-rich runoff and keeping a vegetated buffer strip are the long-term fixes; without them, control becomes a yearly chore.

Checked Oct 4, 2026 · Source: Filamentous Algae (updated May 19, 2025) and the companion Penn State plant fact sheets This may be outdated

Remove it by hand or machine

PFBC recommends physical removal for small areas such as around docks and launches.

Biological options

None effective.

Chemical options (permit first)

Penn State notes large floating plants like spatterdock can be treated later in summer than most plants. Any herbicide or algaecide in a pond needs a joint DEP/PFBC Chapter 91 permit first, at any amount. Only products registered with the U.S. Environmental Protection Agency and with the Pennsylvania Department of Agriculture, and labeled specifically for aquatic use, can be listed on the Chapter 91 permit application.

Checked Oct 4, 2026 · Sources: Water Quality Permitting for Pesticide Applications in Pennsylvania: FAQ (rev. Feb 21, 2025), FAQ #2, #3, #8, #10, #11, #28, #29; Permit Requirement for Use of an Aquatic Herbicide in Ponds (updated Sep 8, 2025) This may be outdated

Follow the product label; the label is the law. A Chapter 91 permit is required before any herbicide or algaecide goes in a pond (see fact). Consider a licensed applicator.

Sources

Checked Oct 4, 2026