Plant Image
Flower spikes and leaves

Yavapai County Native & Naturalized Plants

Potamogeton nodosus - longleaf pondweed

Synonyms: Potamogeton americanus, Potamogeton fluitans, Potamogeton oblongifolius
Other Common Names: knotty pondweed
Plant Form: Forb

Family: Potamogetonaceae

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Leaves and flower spike
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 191
Max Licher @
Forb Plant Description

Origin: Native   Life Cycle: Perennial
General Desc: Widely spread aquatic perennial having submerged branching stems about 2 to 8 feet long with both submerged and floating leaves born on long leaf stems, a distinctive feature. Rhizomes present.
Identification notes: Perennial fresh or brackish plant with jointed stems; submerged narrow to ovate leaves up to 1/8 inch wide with a stem and a blade; floating leaves are broad and leathery with long stems.
Height: 1 to 8 foot spread


Habitat Description: Appearing in clear to turbid waters of lakes, streams, rivers and sloughs. Frequent in ditches, streams, and lakes.
Plant Communities: Riparian
Elevation: 1500 - 8000 feet

Flower Characteristics

Color: Greenish, whitish     Shape: Other in elongated clusters     Tubular: N     Flowering Period: May - Aug
Description: Spikes of tiny flowers from the axils of floating leaves rise above the surface of the water. Spikes are 3/4 to 2 inches long.

Leaf and Stem Characteristics

Leaf Color: Green     Leaf Type: Simple     Leaf Shape: Round or oval     Leaf Margin: Smooth     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: No     Spines: N
Leaf Description: Waxy-shiny, elliptic to ovate, stalked, and leathery. Stems are green to pale yellow.

Fruit and Seed Characteristics

Fruit Color: Reddish-brown   
Fruit Type: Achene
Fruit Notes: Tiny, less than 1/8 inch long and wide; usually one seeded and does not separate or split open at maturity.

  Arizona Cooperative Extension
Yavapai County
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Version 7.0  
Last Updated: May 10, 2017  
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