Potamogeton zosteriformis


Memoirs of the american academy of arts and science n.s. 17:36. 1932.

Common names: Flatstem pondweed potamot zostériforme
Synonyms: Potamogeton zosterifolius subsp. zosteriformis (Fernald) Hultén Potamogeton zosterifolius var. americanus A. Bennett
Treatment appears in FNA Volume 22.

Rhizomes absent. Cauline stems conspicuously flattened ("wing-flattened"), without spots, 60–120 cm; glands absent or rarely present, when present, gold, 0.3 mm diam. Turions common, terminal or lateral, 4–7.5 × 2–4.5 cm, firm; leaves ± 2-ranked; outer leaves 3–4 per side, base not corrugate, apex acute; inner leaves undifferentiated. Leaves submersed, ± spirally arranged, sessile, rigid; stipules persistent, conspicuous, convolute, free from blade, white, not ligulate, 1.5–3.5 cm, fibrous, shredding at tip, apex obtuse to acuminate; blade light green, linear, not arcuate, 10–20 cm × 2–5 mm, base rounded, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, blunt, acuminate, or bristle-tipped, lacunae absent; veins 15–35. Inflorescences unbranched, emersed; peduncles not dimorphic, terminal, erect to ascending, occasionally recurved, cylindric, 2–5 cm; spikes not dimorphic, cylindric, 15–30 mm. Fruits light green to olive-green, quadrate-oblong or nearly orbicular, turgid, sessile, with abaxially keeled, not laterally keeled, 4–5 × 3–3.5 mm, keel winglike; beak erect, 0.6–1 mm; sides without basal tubercles; embryo with 1 full spiral. 2n = 52.

Phenology: Flowering summer–fall.
Habitat: Lakes, ponds, and slow streams
Elevation: 0–15003000 m


V22 16-distribution-map.jpg

Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon, Alaska, Calif., Conn., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mont., Nebr., Nev., N.H., N.J., N.Y., N.Dak., Ohio, Oreg., Pa., S.Dak., Utah, Vt., Wash., Wis., Wyo.


One hybrid, Potamogeton zosteriformis × P. strictifolius, has been described and has been given the name P. ×haynesii Hellquist & G. E. Crow and is known from northern Michigan, Minnesota, Vermont, and southern Canada.

Lower Taxa

... more about "Potamogeton zosteriformis"
Robert R. Haynes +  and C. Barre Hellquist +
Fernald +
Flatstem pondweed +  and potamot zostériforme +
Alta. +, B.C. +, Man. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.W.T. +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Yukon +, Alaska +, Calif. +, Conn. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Maine +, Mass. +, Mich. +, Minn. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.J. +, N.Y. +, N.Dak. +, Ohio +, Oreg. +, Pa. +, S.Dak. +, Utah +, Vt. +, Wash. +, Wis. +  and Wyo. +
0–15003000 m +
Lakes, ponds, and slow streams +
Flowering summer–fall. +
Memoirs of the american academy of arts and science +
hellquist1986a +
Illustrated +  and Endemic +
Potamogeton zosterifolius subsp. zosteriformis +  and Potamogeton zosterifolius var. americanus +
Potamogeton zosteriformis +
Potamogeton +
species +