Potamogeton ogdenii
Potamogeton confervoides
Ogden's pondweed, potamot d'Ogden
alga pondweed, alga-like pondweed, potamot confervoide, Tuckerman's pondweed
absent.
obvious.
compressed-filiform, without spots, to 50 cm;
glands green, golden brown to dark brown, 0.2–0.6 mm diam.
terete, without spots, 10–80 cm.
terminal or lateral, uncommon, 3.7–9.9 × 2.6–6 cm, soft to hard;
leaves flattened with outer and inner leaves in same plane;
outer leaves 1–2 per side, base not corrugate, apex apiculate;
inner leaves undifferentiated or rolled into hardened, fusiform structure.
present, in axils of old leaves and from disintegrating branches, fusiform, 0.7–2 cm, leaves spreading to ascending.
submersed, ± spirally arranged, sessile, rigid;
stipules persistent, inconspicuous, convolute, free from blade, brown or rarely white, not ligulate, 0.9–2.1 cm, slightly fibrous, partially shredding at tip, apex obtuse;
blade somewhat reddish to olive-green, linear, not arcuate, 1.5–10 cm × 1.2–2.9 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, cuspidate to bristle-tipped, lacunae present or absent, in 0–3 rows each side of midvein;
veins 3–9(–13).
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 or occasionally axillary, erect or rarely recurved, slightly clavate, 1–3 cm;
spikes not dimorphic, cylindric, 5–11 mm.
unbranched, emersed;
peduncles not dimorphic, terminal, ascending, somewhat clavate, (3–)5–25 cm;
spikes not dimorphic, capitate, 5–12 mm.
sessile, dark green, orbicular, turgid, abaxial keel obscure, lateral keels obscure or absent, 2.5–3 × 2.2–3 mm, lateral keels if present without points;
beak erect, 0.5 mm;
sides without basal tubercles;
embryo with 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.
unknownnot available.
apparently unknown not available.
Potamogeton ogdenii
Potamogeton confervoides
Potamogeton ogdenii is an extremely local species, probably known from fewer than a dozen localities. The species is herein reported for the first time from Canada, being known from that country by a single collection made in 1987.
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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