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Greenland pondweed

snail-seed pondweed

Rhizomes

absent.

present.

Cauline stems

terete, without spots, 20–50 cm;

glands white, 0.1–0.7 mm diam.

compressed, without spots, 10–25 cm;

glands absent.

Turions

terminal or axillary, common, 4.2–8.4 cm × 1.4–2.5 mm, soft;

leaves ± 4-ranked;

outer leaves 2 per side, base without corrugations, apex acute to apiculate;

inner leaves unmodified.

absent.

Leaves

submersed, ± spirally arranged, sessile, delicate;

stipules deliquescent to persistent, inconspicuous, convolute, free from blade, brown, not ligulate, 0.45–1.91 cm, not fibrous, not shredding at tip, apex obtuse;

blade pale to deep green, linear, not arcuate, 2.6–8.8 cm × 0.7–1.7 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to apiculate, lacunae absent or present, 0–3 rows each side of midrib;

veins 7–11.

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

Floating leaves

petiolate;

petioles continuous in color to apex, 5–35 mm;

blade adaxially light green, lanceolate-elliptic to broadly elliptic, 0.6–2.3(–2.8) cm × 1–11 mm, base tapering or rounded, apex acute to long tapering;

veins 3–7.

Submersed leaves

sessile, lax;

stipules persistent to deliquescent, inconspicuous, convolute, adnate to blade for less than ½ stipule length, light green, ligulate, 0.2–1.2 cm, not fibrous, not shredding at tip, apex obtuse;

blade light green to rarely brown, linear-setaceous, not arcuate, 1.5–11 cm × 0.1–0.4(–0.6) mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, tapering, lacunae absent;

veins 1.

Inflorescences

unbranched, emersed;

peduncles not dimorphic, terminal, erect, cylindric, 20 mm;

spikes not dimorphic, cylindric, 5 mm.

unbranched;

peduncles dimorphic, submersed axillary, somewhat recurved, clavate, 1–10 mm, emersed axillary or terminal, erect to slightly recurved, slightly clavate, 3.5–22 mm;

spikes dimorphic, submersed, globular to ellipsoid, 1.5–7 mm, emersed ellipsoid to cylindric, 3–14 mm.

Fruits

not laterally keeled, 2.6–2.7 × 2 mm;

beak erect, 0.3 mm;

sides without basal tubercles;

embryo with 1 full coil.

sessile, greenish brown, somewhat orbicular, compressed, abaxially keeled, laterally keeled, 1.1–2.1 × 1.1–2 mm, lateral keel without points;

beak absent;

sides without basal tubercles;

embryo with more than 1 full spiral.

2n

= 26.

Potamogeton groenlandicus

Potamogeton bicupulatus

Phenology Flowering late summer. Flowering early summer–fall.
Habitat Ponds and lakes Acidic waters of ponds, lakes, and streams
Elevation 10–450 m (0–1500 ft) 0–300 m (0–1000 ft)
Distribution
from USDA
Greenland
[BONAP county map]
from FNA
CT; DE; IN; MA; ME; MI; NH; NY; PA; RI; TN; VA; VT; WI; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

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

Potamogeton bicupulatus is an uncommon species of the acid lakes and streams of northeastern United States and southern Canada. It is the final third species we have with dimorphic inflorescences and embryos with more than one full spiral. It can be separated from the other two, Potamogeton spirillus and P. diversifolius, because it has very narrow submersed leaves without lacunae and fruits with lateral keels without sharp points.

(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
P. alpinus, P. amplifolius, P. bicupulatus, P. clystocarpus, P. confervoides, P. crispus, P. diversifolius, P. epihydrus, P. floridanus, P. foliosus, P. friesii, P. gramineus, 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
P. alpinus, P. amplifolius, 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
Synonyms P. pusillus subsp. groenlandicus P. diversifolius var. trichophyllus
Name authority Hagström: Kongl. Svenska Vetenskapsakademiens Handlingar n.s. 55(5): 127. (1916) Fernald: Memoirs of the american academy of arts and science 17: 112. (1932)
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