Potamogeton confervoides |
Potamogeton diversifolius |
|
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alga pondweed, alga-like pondweed, potamot confervoide, Tuckerman's pondweed |
diverse-leaf pondweed, Rafinesque's pondweed, water-thread pondweed |
|
Rhizomes | obvious. |
present. |
Cauline stems | terete, without spots, 10–80 cm. |
compressed, without spots, 10–35 cm; glands absent. |
Turions | present, in axils of old leaves and from disintegrating branches, fusiform, 0.7–2 cm, leaves spreading to ascending. |
absent. |
Leaves | 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. |
both submersed and floating or floating absent, ± spirally arranged. |
Floating leaves | petiolate; petioles continuous in color to apex, 0.7–0.8 cm; blade adaxially light green, obovate to elliptic, 0.8–1.6 cm × 3–8.5 mm, base acute, apex round to acute; veins 3–7. |
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Submersed leaves | sessile, lax; stipules persistent to deliquescent, inconspicuous, convolute, adnate to blade ½ stipule length, light brown to red-brown, ligulate, 1.5–2.3 cm, not fibrous, not shredding at tip, apex obtuse; blade red-brown to light green, linear, often arcuate, 1–1.3 cm × 0.1 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae present, 1–2 rows each side midrib; veins 1. |
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Inflorescences | unbranched, emersed; peduncles not dimorphic, terminal, ascending, somewhat clavate, (3–)5–25 cm; spikes not dimorphic, capitate, 5–12 mm. |
unbranched; peduncles dimorphic, submersed axillary, recurved, clavate, 3–5 mm, emersed axillary or terminal, erect to slightly recurved, clavate, 6–15 mm; spikes dimorphic, submersed capitate, 2–3 mm, emersed cylindric, 5–9.7 mm. |
Fruits | 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. |
sessile, greenish brown, orbicular, compressed, abaxially winged, laterally winged, 1–1.5 × 0.9–2 mm, lateral wings with sharp points; beak present, erect, 0.1 mm; sides without basal tubercles; embryo with more than 1 full spiral. |
Chromosome number | apparently unknown not available. |
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Potamogeton confervoides |
Potamogeton diversifolius |
|
Phenology | Flowering early–late summer. | Flowering and fruiting spring–fall. |
Habitat | Acidic waters of bogs, ponds, and lakes, often at higher elevation in e portion of range | Ponds, lakes, streams, and rivers |
Elevation | 0–1500 m (0–4900 ft) | 5–2500 m (0–8200 ft) |
Distribution |
CT; MA; ME; MI; NC; NH; NJ; NY; PA; RI; SC; VT; WI; NB; NL; NS; ON; QC; SPM; St Pierre
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AL; AR; AZ; CA; CO; CT; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; MN; MO; MS; MT; NC; ND; NE; NJ; NV; NY; OH; OK; OR; PA; SC; SD; TN; TX; VA; VT; WI; WV; Mexico; Wyo
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Discussion | 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.) |
Potamogeton diversfolius is very likely the most common species of Potamogeton the genus in the southeastern United States. It has been separated into two species, P. diversifolius in the strict sense and P. capillaceus (M. L. Fernald 1932). The species has also been divided into two varieties, var. diversifolius and var. trichophyllous Morong (D. O S. Correll and M. C. Johnston 1970) . Potamogeton diversifolius var. trichophyllous actually is misapplied, as the name really refers to the more northern P. bicupulatus Fernald. We are following E. J. Klekowski Jr. and E. O. Beal (1965) in accepting only one taxon, as we have studied the species over much of its range and reached similar conclusions. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 22. | FNA vol. 22. |
Parent taxa | Potamogetonaceae > Potamogeton | Potamogetonaceae > Potamogeton |
Sibling taxa | ||
Synonyms | P. tuckermanii | P. capillaceus |
Name authority | Reichenbach: in H. G. L. Reichenbach et al., Icones florae germanicae et helveticae 7: 13. (1845) | Rafinesque: Medical Repository hexade 2, 5:354. (1808) |
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