Aquatic and Wetland Vascular Plants of the Northern Great Plains
55. Potamogetonaceae, the Pondweed Family
1. Potamogeton L. -- Pondweed14. Potamogeton praelongus Wulf. -- Whitestem pondweed
Stems whitish, slightly compressed, 1.5-4 mm thick, sparingly branched, to 2-3 m long, the shorter internodes often zigzag. Leaves all submersed, oblong-lanceolate, 10-25(35) cm long, 1-3 cm wide, with 3-5 primary nerves, rounded and cucullate at the tip, the margin entire and somewhat undulate, sessile and weakly to strongly cordate-clasping at the base; stipules free, whitish, 1-3 cm long, fibrous, early shredding. Spikes dense, cylindric, 2.5-5 cm long; peduncles elongate and thickening upward, 10-40 cm long. Fruits greenish-brown, obovoid, 4-5 mm long, the dorsal keel sharp, the lateral ones obscure. Jun--Jul. Deep water of cold, clear lakes; rare and local from n ND to n NE; (Circumboreal, in N.Amer. s to CT, NY, IN, MN, NE, CO, UT and CA).
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