Burke: Potamogeton richardsonii

	Potamogeton richardsonii
	clasping-leaved pondweed, Richardson's pondweed
Habit	Aquatic, herbaceous perennials from slender rhizomes, the stems sparingly branched, greenish, 1-2 mm. broad and 3-6 dm. long, the internodes only 1-3 cm. long.
Leaves	Leaves alternate, submersed, the blades sessile and clasping, ovate-lanceolate to lanceolate, up to 10 cm. long and 2 cm. broad, with crisp margins, 13-to 25-veined, rounded to acute; stipules free of the leaf, 1-2 cm. long, soon shredding into numerous whitish fibers.
Flowers	Flowers perfect, in 6-12 closely compact whorls, in a spike 1.5-4 cm. long, on a stout peduncle 2-10 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 obovate, about 3 mm. long, faintly keeled on the back, with no lateral keels, the stylar beak nearly 1 mm. long.

	Potamogeton richardsonii
Flowering time	June-August
Habitat	Standing or slow-moving water.
Distribution	Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, northern Great Plains, Great Lakes region, and northeastern 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. natans, P. nodosus, P. obtusifolius, P. praelongus, P. pusillus, 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 richardsonii

clasping-leaved pondweed, Richardson's pondweed

Habit

Aquatic, herbaceous perennials from slender rhizomes, the stems sparingly branched, greenish, 1-2 mm. broad and 3-6 dm. long, the internodes only 1-3 cm. long.

Leaves

Leaves alternate, submersed, the blades sessile and clasping, ovate-lanceolate to lanceolate, up to 10 cm. long and 2 cm. broad, with crisp margins, 13-to 25-veined, rounded to acute;

stipules free of the leaf, 1-2 cm. long, soon shredding into numerous whitish fibers.

Flowers

Flowers perfect, in 6-12 closely compact whorls, in a spike 1.5-4 cm. long, on a stout peduncle 2-10 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 obovate, about 3 mm. long, faintly keeled on the back, with no lateral keels, the stylar beak nearly 1 mm. long.

Potamogeton richardsonii

Flowering time

June-August

Habitat

Standing or slow-moving water.

Distribution

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

[WildflowerSearch map]

[BONAP county map]

Origin

Native

Conservation status

Not of concern

Sibling taxa