OregonFlora: Potamogeton epihydrus

	Potamogeton epihydrus
	ribbon-leaf pondweed, ribbon-leaved pondweed
Stems	flattened, 10–90 cm; nodal glands absent.
Leaves	submersed and floating or submersed only.
Floating leaves	narrowly oblanceolate to elliptic, 20–80 × 4–20 mm; base acute; tip rounded or bluntly cuspidate; veins 11–41; petioles 20–125 mm.
Submersed leaves	sessile, attached to stem nodes, not attached to stipules; stipules 10–30 mm; tip obtuse; blades linear, 50–220 × 1–10 mm; margins entire; tip blunt to acute; lacunae forming a prominent band along the midvein; veins 3–13.
Inflorescences	emersed; spikes cylindric, 8–40 mm; peduncles axillary; erect, 15–50(160)mm.
Fruits	sessile; round to obovoid, flattened, dorsally and laterally keeled, 2.5–4.5 × 2–3.6 mm; greenish brown; beaks erect, 0.5 mm.

	Potamogeton epihydrus
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Still or flowing waters of lakes, ponds and streams. 0–2000m. All ecoregions except Col. CA, ID, WA; north to AK, east to Newfoundland, southeast to FL; Europe. Native. Potamogeton epihydrus is distinguished by submersed linear leaves with a prominent band of lacunae along the midvein. This species hybridizes with P. gramineus and P. nodosus.
Source	Flora of Oregon, volume 1, page 497 Nick Otting, Richard Brainerd, Barbara Wilson
Sibling taxa	P. alpinus, P. amplifolius, P. berchtoldii, P. crispus, P. diversifolius, P. fibrillosus, P. foliosus, P. gramineus, P. illinoensis, P. natans, P. nodosus, P. praelongus, P. pusillus, P. richardsonii, P. robbinsii, P. zosteriformis
Synonyms	Potamogeton epihydrus ssp. nuttallii, Potamogeton epihydrus var. epihydrus, Potamogeton epihydrus var. nuttallii
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Potamogeton epihydrus

ribbon-leaf pondweed, ribbon-leaved pondweed

Stems

flattened, 10–90 cm; nodal glands absent.

Leaves

submersed and floating or submersed only.

Floating leaves

narrowly oblanceolate to elliptic, 20–80 × 4–20 mm;

base acute;

tip rounded or bluntly cuspidate;

veins 11–41;

petioles 20–125 mm.

Submersed leaves

sessile, attached to stem nodes, not attached to stipules;

stipules 10–30 mm;

tip obtuse;

blades linear, 50–220 × 1–10 mm;

margins entire;

tip blunt to acute; lacunae forming a prominent band along the midvein;

veins 3–13.

Inflorescences

emersed;

spikes cylindric, 8–40 mm;

peduncles axillary; erect, 15–50(160)mm.

Fruits

sessile; round to obovoid, flattened, dorsally and laterally keeled, 2.5–4.5 × 2–3.6 mm; greenish brown;

beaks erect, 0.5 mm.

Potamogeton epihydrus

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Still or flowing waters of lakes, ponds and streams. 0–2000m. All ecoregions except Col. CA, ID, WA; north to AK, east to Newfoundland, southeast to FL; Europe. Native.

Potamogeton epihydrus is distinguished by submersed linear leaves with a prominent band of lacunae along the midvein. This species hybridizes with P. gramineus and P. nodosus.

Source

Flora of Oregon, volume 1, page 497
Nick Otting, Richard Brainerd, Barbara Wilson

Sibling taxa