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Greenland pondweed

clasping-leaf pondweed, potamot de Richardson, Richardson's pondweed

Cauline stems

terete, without spots, 20–50 cm;

glands white, 0.1–0.7 mm diam.

terete, without spots, to 100 cm;

nodal 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.

submersed, ± spirally arranged, sessile, lax;

stipules persistent, conspicuous, convolute, free from blade, white, not ligulate, 0.12–0.17 cm, fibrous, disintegrating to persistent fibers, even on proximal portion of stem, shredding at apex, apex obtuse;

blade olive green, ovate-lanceolate to narrowly lanceolate, not arcuate, 1.6–13 cm × 5–28 mm, base rounded, without basal lobes, clasping, margins entire to crispate, apex not hoodlike, not splitting when pressed, acute to obtuse, lacunae absent;

veins 3–35.

Inflorescences

unbranched, emersed;

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

spikes not dimorphic, cylindric, 5 mm.

emersed, unbranched;

peduncles not dimorphic, terminal or axillary, erect to rarely recurved, clavate, 1.5–14.8 cm;

spikes not dimorphic, cylindric, 13–37 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, obovoid, turgid to concave, not or rarely abaxially keeled, not laterally keeled, 2.2–4.2 × 1.7–2.9 mm;

beak erect, 0.4–0.7 mm;

sides without basal tubercles;

embryo with 1 full spiral.

Rhizome(s)

absent.

present.

2n

= 26.

= 52.

Potamogeton groenlandicus

Potamogeton richardsonii

Phenology Flowering late summer. Flowering summer–fall.
Habitat Ponds and lakes Alkaline waters of lakes, streams, and rivers
Elevation 10–450 m (0–1500 ft) 0–3000 m (0–9800 ft)
Distribution
from USDA
Greenland
[BONAP county map]
from FNA
AK; CA; CO; CT; IA; ID; IL; IN; MA; ME; MI; MN; MT; ND; NE; NH; NV; NY; OH; OR; PA; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NS; NT; ON; QC; SK; YT
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

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

Potamogeton richardsonii is quite similar to P. perfoliatus. Specific characteristics to separate the two species are the shape of the leaf blade apex, acute in P. richardsonii and obtuse in P. perfoliatus, and the condition of the stipules, disintegrating between the veins leaving fibrous strands in P. richardsonii, and the entire stipule, including the veins, disintegrating in P. perfoliatus.

Two hybrids, Potamogeton gramineus × P. richardsonii (= P. × hagstroemii A. Bennett [as hagstromii]) and P. nodosus × P. richardsonii (= P. × rectifolius A. Bennett), have been described.

(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. 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. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
Synonyms P. pusillus subsp. groenlandicus P. perfoliatus var. richardsonii, P. perfoliatus subsp. richardsonii
Name authority Hagström: Kongl. Svenska Vetenskapsakademiens Handlingar n.s. 55(5): 127. (1916) (A. Bennett) Rydberg: Bulletin of the Torrey Botanical Club 32: 599. (1905)
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