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Potamogeton gramineus - variableleaf pondweed

Scientific Family
Potamogetonaceae
Synonyms
Potamogeton gramineus var. graminifolius, P. gramineus var. maximus, P. gramineus var. myriophyllus, P. gramineus var. typicus
Other common names
grassy pondweed
grass-leaved pondweed
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Perennial
Height
12 to 32 inches long
Riparian
Yes

Partially submerged aquatic with slender much branched stems, stems terete (cylindrical and tapering) to flattened, 12 to 32 inches long, arising from slender, spreading rhizomes; 2 types of leaves, submerged and floating; flowers emerging above water.

Partially submerged, stems slender, much branched; stipules free from leaf bases; submerged leaves less than 1/8 inch wide, narrow to ovate, stemmed; floating leaves broad and leathery, stemmed; flowers spikes above water, cylindric; 4 greenish tepals.

Habitat

Found in slow moving water, ponds, lakes, streams, and marshy sites.

Plant Community
Riparian
Low elevation
3200
High elevation
11000

Flower Characteristics

Cylindric spike emerging above the water on a stout stalk, 5 to 10-whorled, 3/4 to 4 inches long, with numerous perfect, greenish, stemless flowers, with 4 greenish claw-like tepals, 4 stamens, 2-chambered anthers, 4 edge-to-edge sepal-like outgrowths.

Flower color
Greenish
Flower shape
Regular
Tubular
No
First bloom month
June
Last bloom month
August
Flower clusters
Elongated

Leaf and Stem Characteristics

Stipules free from leaf bases; submerged leaves narrow, soft, 6 to 18 inches long, 5 to 7-veined, light green to brownish-green; floating leaves leathery, stemmed, blades ovate to elliptic, 3/4 to 3 inches long, yellow-green to dark green, 13 veins.

Leaf type
Simple
Leaf color
Green
Leaf shape
Narrow
Leaf margin
Smooth
Leaf attachment
Alternate & Opposite
Leaves clasp
No
Leaf hairs
None
Spines
No

Fruit and Seed Characteristics

Stemless, greenish-brown, rounded and laterally compressed, obscurely ridged laterally and below, about 1/16 inch with erect elongated tip.

Fruit type
Berry-like
Fruit color
Greenish-brown