Potamogeton subsibiricus |
Potamogeton friesii |
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potamot de l'ilenissei, Yenisei River pondweed, Yenissei River pondweed |
flat-stalk pondweed, Fries' pondweed, potamot de Fries |
|
Cauline stems | compressed-filiform, without spots, to 50 cm; glands white, 0.3–0.5 mm diam. |
compressed, without spots, 10–135 cm; glands green, greenish brown, or gold, to 0.7 mm diam. |
Turions | lateral, common, 3.5–9.5 cm × 2–5 mm, soft; leaves ± 2-ranked; outer leaves 3–4 per side, base not corrugate; inner leaves undifferentiated. |
terminal or lateral, common, 1.5–5 cm × 1.5–4 mm, soft; leaves ± 4-ranked; outer leaves 2–3 per side, base corrugate, apex apiculate to acute; inner leaves reduced, arranged into fan-shaped structure and oriented at 90° angles to outer leaves. |
Leaves | submersed, ± spirally arranged, sessile, flaccid; stipules deliquescent, inconspicuous, convolute, free from blade, pale brown, not ligulate, 1–2 cm, not fibrous, not shredding, apex obtuse; blade dark green, linear, not arcuate, 3.5–9.5 cm × 1.5–2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, rounded or nearly acute to mucronate, lacunae in 1–2 rows each side of midvein; veins 9–17. |
submersed, ± spirally arranged, delicate to rigid, sessile; stipules not persistent, inconspicuous, convolute, free from blade, white, not ligulate, 0.55–2.1 cm, fibrous, coarse, shredding at tip, apex obtuse; blade light green, rarely olive-green to.somewhat reddish, linear, not arcuate, 2.3–6.5 cm × 1.2–3.2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to apiculate, lacunae absent or 1 narrow row each side of midrib; veins 5–7(–9). |
Inflorescences | unbranched, emersed; peduncles not dimorphic, axillary, erect, cylindric, 1.7–3.5 cm; spikes not dimorphic, cylindric, 10–30 mm. |
unbranched, emersed; peduncles not dimorphic, terminal or axillary, erect or rarely recurved, slightly clavate, 1.2–4.1(–7) cm; spike not dimorphic, cylindric, 7–16 mm. |
Fruits | sessile, reddish brown, oblong-obovoid, compressed, abaxially ridged, not laterally keeled, 3–4 × 1.5–2 mm; beak nearly erect, 0.3–0.5 mm; sides without basal tubercles; embryo with 1 full coil. |
sessile, olive-green to brown, obovoid, turgid, not abaxially or laterally keeled, 1.8–2.5 × 1.2–2 mm; beak erect, 0.3–0.7 mm; sides without basal tubercles; embryo with 1 full spiral. |
Rhizome(s) | absent. |
absent. |
2n | = 26. |
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Potamogeton subsibiricus |
Potamogeton friesii |
|
Phenology | Fruiting early summer–late summer. | Flowering and fruiting summer–fall. |
Habitat | Shallow water of ponds and lakes | Calcareous to brackish waters of lakes and slow-flowing streams |
Elevation | 0–915 m (0–3000 ft) | 0–3100 m (0–10200 ft) |
Distribution |
AK; MB; NT; NU; ON; QC; YT; Siberia |
AK; CO; CT; IA; ID; IL; IN; MA; ME; MI; MN; MT; ND; NE; NH; NY; OH; PA; RI; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; YT; Eurasia
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Discussion | Potamogeton friesii is a fairly common linear-leaved species, especially of calcareous waters of lakes and streams of the upper Midwest. Whenever turions are present, the species is easily identified, as it is the only one with the outer leaves of the turions having corrugate bases and the inner leaves turned at right angles to the outer leaves. Two hybrids, Potamogeton friesii × P. pusillus (= P. × pusilliformis Fischer [P. × intermedius Fischer]) and P. friesii × P. obtusifolius (= P. × semifructus A. Bennett ex Ascherson & Graebner), have been described. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | P. porsildiorum | |
Name authority | Hagström: Kongl. Svenska Vetenskapsakademiens Handlingar n.s. 44:555(5):84. (1916) | Ruprecht: Hist. Stirp. Fl. Petrop. 43. (1845) |
Web links |