Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
55. Potamogetonaceae, the Pondweed Family
1. Potamogeton L. -- Pondweed
1. Potamogeton alpinus Balbis
Stems terete, 1-2 mm thick, simple or rarely branched above, to 1 m long;
foliage reddish-tinged, especially the upper leaves and peduncles. Submersed
leaves linear-lanceolate to linear-oblong, 4-18 cm long, 5-15(20) mm wide,
usually 7(-11)-nerved, blunt and obtuse to rarely acutish at the tip, narrowed
to a sessile base. Floating leaves often lacking, thin and delicate,
obovate or oblanceolate to elliptic-oblanceolate, mostly 4-6 cm long, 1-2 cm
wide, 7- to 15-nerved, obtuse, tapering indistinctly into a short petiole. Stipules
free, membranous, 1-2.5(4) cm long; spikes cylindric, with 5-9 crowded
whorls of flowers, peduncles about as thick as the stem, 3-15 cm long. Fruits
tawny-olive, obliquely obovoid, 2.5-3.5 mm long; dorsal keel usually narrow
and prominent; lateral keels absent or low and rounded; beak short, curved backward.
Jul--Sep. Cold streams and lakes in the Black Hills; (Circumboreal, in N.Amer.
from Newf. to AK, s to MA, NY, WI, MN, SD, CO, UT and CA).
Reports of P. alpinus for outside of the Black Hills in this region
were based on misidentifications.
Return to Family -- Potamogetonaceae - The
Next Section -- Potamogeton amplifolius Tuckerm.
-- Largeleaf pondweed