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Potamogeton nodosus - longleaf pondweed

Scientific Family
Potamogetonaceae
Synonyms
Potamogeton americanus, Potamogeton fluitans, Potamogeton oblongifolius
Other common names
knotty pondweed
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Perennial
Height
1 to 8 foot spread
Riparian
Yes

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.

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.

Habitat

Appearing in clear to turbid waters of lakes, streams, rivers and sloughs. Frequent in ditches, streams, and lakes.

Plant Community
Riparian
Low elevation
1500
High elevation
8000

Flower Characteristics

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.

Flower color
Greenish, whitish
Flower shape
Other
Tubular
No
First bloom month
May
Last bloom month
August
Flower clusters
Elongated

Leaf and Stem Characteristics

Waxy-shiny, elliptic to ovate, stalked, and leathery. Stems are green to pale yellow.

Leaf type
Simple
Leaf color
Green
Leaf shape
Round or oval
Leaf margin
Smooth
Leaf attachment
Alternate
Leaves clasp
No
Leaf hairs
None
Spines
No

Fruit and Seed Characteristics

Tiny, less than 1/8 inch long and wide; usually one seeded and does not separate or split open at maturity.

Fruit type
Achene
Fruit color
Reddish-brown