Potamogeton tennesseensis |
Potamogeton oblongus |
|
---|---|---|
Tennessee pondweed |
cinnamonspot pondweed, potamot oblong |
|
Cauline stems | terete, without spots, 10–35 cm; glands absent. |
terete, without spots, 5–30 cm; nodal glands absent. |
Turions | absent. |
absent. |
Leaves | both submersed and floating or floating absent, ± spirally arranged. |
both submersed and floating or only submersed, ± spirally arranged. |
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. |
petioles continuous in color to apex, 1–17 cm; blade adaxially reddish brown, ovate, 3–8(–10) cm × 10–46 mm, base rounded or slightly cordate, apex obtuse, acute, or somewhat apiculate; veins (11–)15–19(–21). |
Submersed leaves | 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. |
petiolate, lax; stipules persistent, conspicuous, convolute, free from blade, greenish, not ligulate, to 3 cm, not fibrous, not shredding at tip, apex acute; petioles 1–3(–8) cm; blade dark green, lanceolate to occasionally ovate, occasionally arcuate, 3–13 cm × 4–15(–44) mm, base acute, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae in 2–4 rows each side of midvein; veins 7–11. |
Inflorescences | unbranched, emersed; peduncle not dimorphic, axillary, ascending, cylindric, 3–8 cm; spikes not dimorphic, cylindric, 10–22 mm. |
unbranched, emersed; peduncles not dimorphic, erect to slightly recurved, cylindric, 4–12 cm; spikes not dimorphic, cylindric, 20–40 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. |
sessile, dark reddish brown, obovoid to orbicularoid, compressed, not abaxially or laterally keeled, (1.6–)2–2.5 × (1.2–)1.5–2.1 mm; beak minute or obsolete, recurved; sides without basal tubercles; embryo with 1 full spiral. |
Rhizome(s) | present. |
present. |
2n | = 26. |
|
Potamogeton tennesseensis |
Potamogeton oblongus |
|
Phenology | Flowering mid spring–fall. | Flowering July–August. |
Habitat | Slow- to fast-moving streams and rivers | Acid to neutral waters of ponds, lakes, and occasionally streams |
Elevation | 200–1000 m (700–3300 ft) | 10–100 m (0–300 ft) |
Distribution |
KY; MD; NC; OH; PA; TN; VA; WV |
NF; NS; SPM; Europe; n Africa; Atlantic Islands (Azores) [Introduced in North America] |
Discussion | 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.) |
|
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | ||
Sibling taxa | ||
Name authority | Fernald: Rhodora 38: 167, plate 412. (1936) | Viviani: Annali di Botanica 1(2): 102. (1802) |
Web links |