Potamogeton tennesseensis |
Potamogeton clystocarpus |
|
---|---|---|
Tennessee pondweed |
little aguja pondweed |
|
Rhizomes | present. |
absent. |
Cauline stems | terete, without spots, 10–35 cm; glands absent. |
terete to slightly compressed, without spots, to 57 cm; glands white to gold, 0.2–0.3 mm diam. |
Turions | absent. |
unknown. |
Leaves | both submersed and floating or floating absent, ± spirally arranged. |
submersed, ± spirally arranged, sessile, delicate; stipules persistent, inconspicuous, convolute, free from blade, brown, not ligulate, to 0.62 cm, not fibrous, not shredding at tip, apex obtuse; blade green, linear, not arcuate, 3.2–7.8 cm × 0.7–1.7 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae rarely absent, in 0–4 rows each side of midrib; veins 3(–5). |
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. |
|
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. |
|
Inflorescences | unbranched, emersed; peduncle not dimorphic, axillary, ascending, cylindric, 3–8 cm; spikes not dimorphic, cylindric, 10–22 mm. |
unbranched, emersed; peduncles not dimorphic, axillary or terminal, erect, cylindric, 3.2–4.8 cm; spike not dimorphic, capitate to cylindric, 5.5–7.5 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, brown to yellow-green, obovoid, compressed, abaxially and laterally keeled, 2–2.2 × 1.7–1.8 mm, lateral keels without points; beak erect, 0.5–0.6 mm; sides with 1–3 tubercules near base; embryo with 1 full spiral. |
Potamogeton tennesseensis |
Potamogeton clystocarpus |
|
Phenology | Flowering mid spring–fall. | Flowering and fruiting spring–summer. |
Habitat | Slow- to fast-moving streams and rivers | Small streams |
Elevation | 200–1000 m (700–3300 ft) | ca. 1800 m (ca. 5900 ft) |
Distribution |
KY; MD; NC; OH; PA; TN; VA; WV |
TX |
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.) |
Potamogeton clystocarpus is an extremely limited species known from only one canyon in west Texas. 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) | Fernald: Memoirs of the american academy of arts and science n.s. 17:79, plates 15, 30, fig. 5. (1932) |
Web links |