Burke: Potamogeton natans

	Potamogeton natans
	floating pondweed, floating-leaved pondweed
Habit	Aquatic, herbaceous perennials from slender rhizomes, the stems mostly unbranched, sub-terete, up to 2 mm. thick and 1.5 m. long.
Leaves	Leaves alternate, the submersed leathery, sub-terete, narrowly linear, 10-20 cm. long and 1-2 mm. broad; floating leaves long-petioled, leathery, ovate-lanceolate to ovate-elliptic, rounded to nearly cordate at the base, 5-10 cm. long and 2.5-5 cm. broad, 19- to 35-nerved; stipules firm, fibrous, 4-10 cm. long.
Flowers	: Flowers perfect, in densely-flowered spikes in 10-12 whorles, on stout peduncles 3-8 cm. long; perianth of 4 clawed segments, each with an upturned, oval blade; stamens 4, fused with the claws; pistils 4, sessile.
Fruits	Achenes obliquely elliptic-obovoid, 3-5 mm. long, including the conical, stylar beak, rounded on the back.

	Potamogeton natans
Flowering time	June-August
Habitat	In rather shallow, standing water, often where brackish.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, Great Plains, Great Lakes Region, and eastern North America. [WildflowerSearch map] [BONAP county map]
Origin	Native
Conservation status	Not of concern
Sibling taxa	P. alpinus, P. amplifolius, P. berchtoldii, P. crispus, P. epihydrus, P. fibrillosus, P. foliosus, P. friesii, P. gramineus, P. illinoensis, P. nodosus, P. obtusifolius, P. praelongus, P. pusillus, P. richardsonii, P. robbinsii, P. strictifolius, P. zosteriformis
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 natans

floating pondweed, floating-leaved pondweed

Habit

Aquatic, herbaceous perennials from slender rhizomes, the stems mostly unbranched, sub-terete, up to 2 mm. thick and 1.5 m. long.

Leaves

Leaves alternate, the submersed leathery, sub-terete, narrowly linear, 10-20 cm. long and 1-2 mm. broad; floating leaves long-petioled, leathery, ovate-lanceolate to ovate-elliptic, rounded to nearly cordate at the base, 5-10 cm. long and 2.5-5 cm. broad, 19- to 35-nerved;

stipules firm, fibrous, 4-10 cm. long.

Flowers

: Flowers perfect, in densely-flowered spikes in 10-12 whorles, on stout peduncles 3-8 cm. long;

perianth of 4 clawed segments, each with an upturned, oval blade;

stamens 4, fused with the claws;

pistils 4, sessile.

Fruits

Achenes obliquely elliptic-obovoid, 3-5 mm. long, including the conical, stylar beak, rounded on the back.

Potamogeton natans

Flowering time

June-August

Habitat

In rather shallow, standing water, often where brackish.

Distribution

Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, Great Plains, Great Lakes Region, and eastern North America.

[WildflowerSearch map]

[BONAP county map]

Origin

Native

Conservation status

Not of concern

Sibling taxa