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big-leaf pondweed, broad-leaf pondweed, large-leaf pondweed, potamot à grandes feuilles

Rhizomes

present.

Cauline stems

terete, often rusty spotted, 6–110 cm;

nodal glands absent.

Turions

absent.

Leaves

both submersed and floating or floating absent, ± spirally arranged.

Floating leaves

petioles continuous in color to apex, 2.3–22.6 cm;

blade adaxially light green, lanceolate to round elliptic, 4.3–9.2 cm × 25–38 mcm, base rounded to cordate, apex acute to rounded;

veins 27–49.

Submersed leaves

petiolate, lax;

stipules persistent, conspicuous, convolute, free from blade, light brown, not ligulate, 1.5–11.7 cm, not fibrous, not shredding at tip, apex acute;

petioles terete, 0.9–11.5 cm;

blade light to dark green, ovate to oblanceolate, distinctly arcuate, 5–12.5 cm × 15–58 mm, base rounded to acute, without basal lobes, not clasping, margins entire, crispate, apex not hoodlike, acute to round-apiculate, lacunae absent;

veins 19–49.

Inflorescences

unbranched, emersed;

peduncles not dimorphic, terminal or axillary, erect, cylindric, 4.5–22.3 cm;

spikes not dimorphic, cylindric, 34–65 mm.

Fruits

sessile, reddish brown, obovoid, turgid, abaxially keeled, laterally ridged, 5–6.7 × 4.5–5.2 mm, lateral ridges without points;

beak erect, 0.5–0.8 mm;

sides without basal tubercles;

embryo with full spiral.

2n

= 52.

Potamogeton amplifolius

Phenology Flowering summer–fall.
Habitat Waters of lakes, ponds, streams, and rivers
Elevation 0–1900(–2900) m (0–6200(–9500) ft)
Distribution
from FNA
AL; AR; CA; CT; GA; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; NC; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SD; TN; VA; VT; WA; WI; WV; WY; BC; MB; NB; NF; NS; ON; QC; SK
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Discussion

No specimens have been seen from Kentucky or Texas, but the species is to be expected there.

Potamogeton amplifolius is common throughout much of North America. Its submersed leaves are larger than those of most other species of Potamogeton, are arcuate, and have more veins than do any other species.

One hybrid, Potamogeton amplifolius × P. illinoensis (= P. × scoliophyllus Hagström), has been described.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 22.
Parent taxa Potamogetonaceae > Potamogeton
Sibling taxa
P. alpinus, P. bicupulatus, P. clystocarpus, P. confervoides, P. crispus, P. diversifolius, P. epihydrus, P. floridanus, P. foliosus, P. friesii, P. gramineus, P. groenlandicus, P. hillii, P. illinoensis, P. natans, P. nodosus, P. oakesianus, P. oblongus, P. obtusifolius, P. ogdenii, P. perfoliatus, P. praelongus, P. pulcher, P. pusillus, P. richardsonii, P. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
Name authority Tuckerman: American Journal of Science, and Arts ser. 2, 6:225. (1848)
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