Potamogeton strictifolius

Rhizomes absent. Cauline stems terete, without spots, 27–95 cm; glands white, green, greenish brown, or gold, to 0.3 mm diam. Turions terminal or lateral, common, 2.5–4.8 cm × 0.8–2.2 mm, soft; leaves ± 2-ranked, flattened with outer and inner leaves in same plane; outer leaves 3–4 per side, base not corrugate, or rarely corrugate, apex acute; inner leaves undifferentiated. Leaves submersed, ± spirally arranged, rigid, sessile; stipules disintegrating, inconspicuous, connate, free from blade, white, not ligulate, 0.6–1.6 cm, fibrous, shredding at tip, apex obtuse; blade green to olive-green, linear, not arcuate, 1.2–6.3 cm × 0.6–2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to nearly bristle-tipped, rarely obtuse to apiculate, lacunae absent; veins 3–5(–7). Inflorescences unbranched, emersed; peduncles not dimorphic, terminal, erect, rarely recurved, cylindric, rarely slightly clavate, 1–4.5 cm; spike not dimorphic, cylindric, 0.6–1.3 cm. Fruits sessile, green-brown, ovoid, turgid, not abaxially or laterally keeled, 1.9–2.1 × 1.3–1.8 mm; beak erect, 0.5–0.8 mm; sides without basal tubercles; embryo with 1 full spiral. 2n = 26.

Phenology: Flowering and fruiting summer–fall.
Habitat: Alkaline waters of lakes and slow-moving streams
Elevation: 50–2000 m

Distribution

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Alta., Man., N.B., Ont., Que., Sask., Yukon, Conn., Ill., Ind., Maine, Mass., Mich., Minn., Nebr., N.Y., N.Dak., Ohio, Pa., S.Dak., Utah, Vta., Vat., Wis., Wyo.

Discussion

Potamogeton strictifolius is a relatively uncommon species found in alkaline waters. Fairly rigid leaves of the species make floating onto paper unnecessary in the collecting process. The leaves have a tendency to become revolute during the growing season. The species superficially resembles several other species of linear-leaved pondweeds. Consequently, many specimens of this species have been misidentified as other species and vice versa. Thus, literature records are often suspect.

One hybrid, Potamogeton strictifolius × P. zosteriformis (= P. × haynesii Hellquist & G. E. Crow), has been described.

Selected References

None.

Lower Taxa

None.