Potamogeton tennesseensis
Potamogeton floridanus
Tennessee pondweed
Florida pondweed
present.
present.
terete, without spots, 10–35 cm;
glands absent.
terete, without spots, ca. 50 cm.
absent.
unknown.
both submersed and floating or floating absent, ± spirally arranged.
submersed and floating, ± spirally arranged.
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.
petioles continuous in color to apex, 4–6.5 cm;
blade adaxially dark brown, elliptic, 4.5–6.6 cm × 7–12 mm;
base acute, apex acute;
veins 7–11.
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.
sessile, lax;
stipules persistent, inconspicuous, convolute, free from blade, whitish, not ligulate, 2.5–4 cm, delicately fibrous, eventually shredding, apex acute;
blade dark green to olive-green, narrowly linear, not arcuate, 15–20 cm × 0.7 mm, base attenuate, not clasping, not lobed, margins entire, not crispate, apex not hoodlike, acute, lacunae absent;
veins 1.
unbranched, emersed;
peduncle not dimorphic, axillary, ascending, cylindric, 3–8 cm;
spikes not dimorphic, cylindric, 10–22 mm.
unknown.
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.
unknown.
Potamogeton tennesseensis
Potamogeton floridanus
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 floridanus is an extremely localized species of the panhandle of Florida. No one has treated the species recently (E. C. Ogden 1943; R. R. Haynes 1978). Four populations of the taxon were reported from Santa Rosa County, Florida (G. S. Wilhelm and R. H. Mohlenbrock 1986). Those populations clearly match the protologue and the original collections. One population has recently been found fertile (J. R. Burckhalter, pers. comm.), but we have not examined the specimens. Because the taxon persists and has a vegetative morphology unlike any other pondweed, we believe it must be recognized. Until a better understanding of the taxon is developed, we prefer to recognize it at the specific level.
Of conservation concern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
MD Biodiversity
WildflowerSearch
iNaturalist
USDA Plants Database
