UW Burke Herbarium species comparison

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Potamogeton alpinus

Potamogeton crispus

northern pondweed, reddish pondweed

curly pondweed
Habit Annual, perennial herb, slender, rhizomed; stems greater than 100 cm, branched, branches not many, cylindric. Aquatic, herbaceous perennials from slender rhizomes, the stems branching, somewhat flattened, 4-8 dm. long and 1-2 mm. broad.
Leaves

Various shades of red; submersed sessile, 2-8 x 1-2 cm, lanceolate to elliptic-oblong, tapered to both ends, entire, tip blunt, veins 7-9; floating 0 or short-petioled, lanceolate, base tapered, veins 7-15;

stipules beyond 3 cm, free, membranous, early-deciduous.

: Leaves alternate, all submersed, narrowly oblong, 3-8 cm. long and 3-10 mm. broad, strongly crisped, finely serrulate on the upper margins, rounded at the tip, sessile and clasping, 3- to 5-nerved;

stipules delicate, 4-8 mm. long.
Flowers

Inflorescence generally < 3 cm, floating to emergent;

peduncle stiff.

Flowers perfect, in spikes 1-2 cm. long on peduncles 3-5 cm. long;

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

stamens 4, fused with the claws;

pistils 4, sessile.
Fruit(s)

Around 2.5 mm, keels 1 or 3, generally, beaked, sides concave to convex.

Achenes ovoid, 3 mm. long, with 3 obtuse but prominent keels, tapered into a beak 2-3 mm. long.
Comments

One hybrid, Potamogeton crispus × P. praelongus (= P. ×undulatus Wolfgang ex Schultes & Schultes f.), has been described.

Potamogeton alpinus

Potamogeton crispus
Flowering time June-August June-August
Habitat Calm water of lakes and slow streams. Slow-moving rivers and streams, lakes, ponds, and backwater channels, generally at low elevations.
Distribution
Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains and northern Great Plains; also in eastern North America.
[WildflowerSearch map]
[BONAP county map]
Widely dsitributed on both sides of the Cascades crest in Washington; British Columbia to California, east across North America to the Atlantic Coast.
[WildflowerSearch map]
[BONAP county map]
Origin Native Introduced from Eurasia
Conservation status Not of concern Not of concern
Sibling taxa
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. richardsonii, P. robbinsii, P. strictifolius, P. zosteriformis
P. alpinus, P. amplifolius, P. berchtoldii, P. epihydrus, P. fibrillosus, P. foliosus, P. friesii, P. gramineus, P. illinoensis, P. natans, P. nodosus, P. obtusifolius, P. praelongus, P. pusillus, P. richardsonii, P. robbinsii, P. strictifolius, P. zosteriformis
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Unless otherwise noted, all data comes from the University of Washington's Burke Herbarium.



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