Pygmy Water-lily (Nymphaea tetragona) — identification, habitat & look-alikes

Pygmy Water-lily is a small water plant found in ponds, lakes, and quiet streams in northwestern and far northern North America. Its small white flowers bloom in summer near the water surface, above round leaves with a deep notch at the base. Its only recorded population in the contiguous United States is believed to be gone.

Appearance

Growth form: This perennial water plant grows from a short anchored in bottom sediment.
Leaves: The floating leaves are oval to nearly round with a deep notch at the base. Young leaves may show mottling.
Flowers: The white flowers are small for a water-lily and have a distinctly four-angled base. The stamens and pistil are often purple-toned.
Flowering time: In northern North America it flowers in summer.
Fruit: After flowering, the fruit develops below the water surface.

Look-alikes

dwarf water-lilyNymphaea leibergii

Look for the flower base: Pygmy Water-lily has four clear angles, while dwarf water-lily has a rounder base. The two can be hard to tell apart when that part is hidden in a photo.

Why they get mixed upBoth are small northern water-lilies with white flowers and similarly shaped floating leaves.

Where it lives

Typical habitats: ponds
lakes
quiet streams
Range: In North America it is a northwestern and subarctic species. It occurs in Alaska and Canada; one old Washington collection is believed to represent a population now gone from the contiguous United States.
Preferred conditions: It grows in still or slow water from low elevations to about 3,900 ft (1,200 m).

Name and classification

About the name: Many eastern North American records once identified as Nymphaea tetragona are now assigned to dwarf water-lily (Nymphaea leibergii).

Conservation

IUCN Red List: LCLeast ConcernLow risk of extinction
Status: The species is very rare at the southern edge of its North American range.

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