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FNA | Family List | FNA Vol. 22 | Potamogetonaceae | Potamogeton

5. Potamogeton tennesseensis Fernald, Rhodora. 38: 167, plate 412. 1936.

Tennessee pondweed

Rhizomes present. Cauline stems terete, without spots, 10--35 cm; glands absent. Turions absent. Leaves both submersed and floating or floating absent, ± spirally arranged. Submersed leaves sessile, lax; stipules persistent, inconspicuous, convolute, adnate to blade for ΒΌ 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. Floating leaves 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. Inflorescences unbranched, emersed; peduncle not dimorphic, axillary, ascending, cylindric, 3--8 cm; spikes not dimorphic, cylindric, 10--22 mm. Fruits 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.

Flowering mid spring--fall. Slow- to fast-moving streams and rivers; of conservation concern; 200--1000 m; Ky., Md., N.C., Ohio, Pa., Tenn., Va., W.Va.

No specimens have been seen from Maryland although the species is to be expected there.


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