Potamogeton diversifolius |
Potamogeton zosteriformis |
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diverse-leaf pondweed, Rafinesque's pondweed, water-thread pondweed |
eel-grass pondweed, flat-stem pondweed, potamot zostériforme |
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Rhizomes | present. |
absent. |
Cauline stems | compressed, without spots, 10–35 cm; glands absent. |
conspicuously flattened ("wing-flattened"), without spots, 60–120 cm; glands absent or rarely present, when present, gold, 0.3 mm diam. |
Turions | absent. |
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 | both submersed and floating or floating absent, ± spirally arranged. |
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. |
Floating leaves | petiolate; petioles continuous in color to apex, 0.7–0.8 cm; blade adaxially light green, obovate to elliptic, 0.8–1.6 cm × 3–8.5 mm, base acute, apex round to acute; veins 3–7. |
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Submersed leaves | sessile, lax; stipules persistent to deliquescent, inconspicuous, convolute, adnate to blade ½ stipule length, light brown to red-brown, ligulate, 1.5–2.3 cm, not fibrous, not shredding at tip, apex obtuse; blade red-brown to light green, linear, often arcuate, 1–1.3 cm × 0.1 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae present, 1–2 rows each side midrib; veins 1. |
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Inflorescences | unbranched; peduncles dimorphic, submersed axillary, recurved, clavate, 3–5 mm, emersed axillary or terminal, erect to slightly recurved, clavate, 6–15 mm; spikes dimorphic, submersed capitate, 2–3 mm, emersed cylindric, 5–9.7 mm. |
unbranched, emersed; peduncles not dimorphic, terminal, erect to ascending, occasionally recurved, cylindric, 2–5 cm; spikes not dimorphic, cylindric, 15–30 mm. |
Fruits | sessile, greenish brown, orbicular, compressed, abaxially winged, laterally winged, 1–1.5 × 0.9–2 mm, lateral wings with sharp points; beak present, erect, 0.1 mm; sides without basal tubercles; embryo with more than 1 full spiral. |
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. |
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Potamogeton diversifolius |
Potamogeton zosteriformis |
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Phenology | Flowering and fruiting spring–fall. | Flowering summer–fall. |
Habitat | Ponds, lakes, streams, and rivers | Lakes, ponds, and slow streams |
Elevation | 5–2500 m (0–8200 ft) | 0–15003000 m (0–49222400 ft) |
Distribution |
AL; AR; AZ; CA; CO; CT; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; MN; MO; MS; MT; NC; ND; NE; NJ; NV; NY; OH; OK; OR; PA; SC; SD; TN; TX; VA; VT; WI; WV; Mexico; Wyo
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AK; CA; CT; IA; ID; IL; IN; KS; MA; ME; MI; MN; MT; ND; NE; NH; NJ; NV; NY; OH; OR; PA; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; YT
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Discussion | Potamogeton diversfolius is very likely the most common species of Potamogeton the genus in the southeastern United States. It has been separated into two species, P. diversifolius in the strict sense and P. capillaceus (M. L. Fernald 1932). The species has also been divided into two varieties, var. diversifolius and var. trichophyllous Morong (D. O S. Correll and M. C. Johnston 1970) . Potamogeton diversifolius var. trichophyllous actually is misapplied, as the name really refers to the more northern P. bicupulatus Fernald. We are following E. J. Klekowski Jr. and E. O. Beal (1965) in accepting only one taxon, as we have studied the species over much of its range and reached similar conclusions. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | Potamogetonaceae > Potamogeton | Potamogetonaceae > Potamogeton |
Sibling taxa | ||
Synonyms | P. capillaceus | P. zosterifolius subsp. zosteriformis, P. zosterifolius var. americanus |
Name authority | Rafinesque: Medical Repository hexade 2, 5:354. (1808) | Fernald: Memoirs of the american academy of arts and science n.s. 17:36. (1932) |
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