Potamogeton groenlandicus
Potamogeton confervoides
Greenland pondweed
alga pondweed, alga-like pondweed, potamot confervoide, Tuckerman's pondweed
absent.
obvious.
terete, without spots, 20–50 cm;
glands white, 0.1–0.7 mm diam.
terete, without spots, 10–80 cm.
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.
present, in axils of old leaves and from disintegrating branches, fusiform, 0.7–2 cm, leaves spreading to ascending.
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, flaccid, sessile;
stipules deliquescent, inconspicuous, convolute, free from blade, pale green, not ligulate, 0.5–1.2 cm, not fibrous, not shredding at tip, apex obtuse;
blade pale green, linear, not arcuate, 1.8–6.5 cm × 0.1–0.5 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, extremely attenuate, bristly, lacunae present, each side of midvein to margins;
veins 1.
unbranched, emersed;
peduncles not dimorphic, terminal, erect, cylindric, 20 mm;
spikes not dimorphic, cylindric, 5 mm.
unbranched, emersed;
peduncles not dimorphic, terminal, ascending, somewhat clavate, (3–)5–25 cm;
spikes not dimorphic, capitate, 5–12 mm.
not laterally keeled, 2.6–2.7 × 2 mm;
beak erect, 0.3 mm;
sides without basal tubercles;
embryo with 1 full coil.
sessile, light green, round-obovoid or nearly orbicular, compressed, abaxially and laterally keeled, 2–3 × 1.7–2.8 mm, lateral keels without sharp point;
beak erect, 0.5 mm;
sides without basal tubercles;
embryo with less than 1 full spiral.
apparently unknown not available.
= 26.
Potamogeton groenlandicus
Potamogeton confervoides
Of conservation concern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potamogeton confervoides is most uncommon and found only in fairly acidic waters. It is easily recognized by its linear, bristly leaves and the unusually long peduncle that seems out of place on a plant with such fine leaves. The leaves are so fine that they almost appear as greenish colored hair in the water. When the plant is removed from the water, the leaves are extremely flaccid leaves and essentially collapse onto each other.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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