Potamogeton tennesseensis
Potamogeton confervoides
Tennessee pondweed
alga pondweed, alga-like pondweed, potamot confervoide, Tuckerman's pondweed
present.
obvious.
terete, without spots, 10–35 cm;
glands absent.
terete, without spots, 10–80 cm.
absent.
present, in axils of old leaves and from disintegrating branches, fusiform, 0.7–2 cm, leaves spreading to ascending.
both submersed and floating or floating absent, ± spirally arranged.
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.
petiolate;
petioles continuous in color to apex, 2.5–6 cm;
blade greenish brown adaxially, lance-oblong, 2–4(–5.5) cm × 5–13 mm, base acute, apex acute;
veins 9–23.
sessile, lax;
stipules persistent, inconspicuous, convolute, adnate to blade for ¼ or less stipule length, light brown to dark green, ligulate, 0.5–1.5 cm, not fibrous, not shredding at tip, apex acute;
blade red-brown to dark green, linear-filiform, not arcuate, 2.5–10.5 cm × 0.2–1(–2) mm, base slightly tapering, not clasping, without basal lobes, margins entire, not crispate, apex not hoodlike, long tapering, lacunae abundant, broad, filling area between margin and midvein;
veins 1–3.
unbranched, emersed;
peduncle not dimorphic, axillary, ascending, cylindric, 3–8 cm;
spikes not dimorphic, cylindric, 10–22 mm.
unbranched, emersed;
peduncles not dimorphic, terminal, ascending, somewhat clavate, (3–)5–25 cm;
spikes not dimorphic, capitate, 5–12 mm.
sessile, greenish brown, quadrate-orbicular, slightly compressed, abaxially keeled, laterally ridged, 2.5–3 × 2–2.5 mm;
lateral ridges without points;
beak present, erect, 0.5 mm;
sides without basal tubercles;
embryo with less than 1 full spiral.
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.
Potamogeton tennesseensis
Potamogeton confervoides
No specimens have been seen from Maryland although the species is to be expected there.
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.)
MD Biodiversity
WildflowerSearch
iNaturalist
USDA Plants Database
Go Botany
MI Flora
