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alpine pondweed, northern pondweed, potamot alpin, reddish pondweed

diverse-leaf pondweed, Rafinesque's pondweed, water-thread pondweed

Cauline stems

terete, without spots, to 200 cm;

nodal glands absent.

compressed, without spots, 10–35 cm;

glands absent.

Turions

absent.

absent.

Leaves

submersed and floating or floating absent, ± spirally arranged.

both submersed and floating or floating absent, ± spirally arranged.

Floating leaves

petioles continuous in color to apex, 0.1–1.2 cm;

blade reddish green, elliptic or oblanceolate to obovate or oblong-linear, 4–7(–10) cm × 10–25(–40) mm, base gradually tapering into petiole, apex obtuse or acute;

veins (7–)9–13(–15).

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.

Submersed leaves

sessile, lax;

stipules persistent, inconspicuous, convolute, free from blade, light brown to reddish, not ligulate, (1.2–)1.5–2.5(–4) cm, not fibrous, not shredding at tip, apex blunt;

blade reddish green, oblong-linear to linear-lanceolate, not arcuate, 4.5–18(–25) cm × 5–20 mm, base rounded, without basal lobes, slightly clasping, margins entire, not crispate, apex not hoodlike, obtuse or acute, lacunae in 0–6 rows each side of midvein;

veins 7–9.

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.

Inflorescences

unbranched, emersed;

peduncles not dimorphic, terminal or axillary, erect, cylindric, 3–10(–16) cm;

spikes not dimorphic, cylindric, 10–35 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

pedicellate, tawny olive-green, obovoid, plump, turgid, abaxially keeled, laterally keeled or not, (2.5–)3–3.5 × (1.7–)2–2.4 mm, lateral keels when present without points;

beak abaxially curved, 0.5–0.9 mm;

sides without basal tubercles;

embryo with 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.

Rhizome(s)

present.

present.

2n

= 52.

Potamogeton alpinus

Potamogeton diversifolius

Phenology Flowering early summer–fall. Flowering and fruiting spring–fall.
Habitat Ponds, lakes, and slow-moving streams Ponds, lakes, streams, and rivers
Elevation 400–2500 m (1300–8200 ft) 5–2500 m (0–8200 ft)
Distribution
from FNA
AK; CA; CO; ID; MA; ME; MI; MN; MT; NH; NJ; NV; NY; OR; PA; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; Greenland; Europe; Asia Eurasia
[WildflowerSearch map]
[BONAP county map]
from FNA
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
[WildflowerSearch map]
[BONAP county map]
Discussion

Plants of Potamogeton alpinus often are red whenever taken from the water, a feature that makes this species quite distinctive.

Two varieties, Potamogeton alpinus var. tenuifolius and var. subellipticus, have been recognized in North America, based mainly on submersed leaf shape. Plants bearing both leaf types have been observed in the same population; hence the varieties are not recognized.

Four hybrids, Potamogeton alpinus × P. nodosus (= P. ×subobtusus Hagström), P. alpinus × P. gramineus (= P. xnericius Hagström), P. alpinus × P. praelongus (= P. ×griffithii A. Bennett), and P. alpinus × P. perfoliatus (= P. ×prussicus Hagström), have been described.

(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
P. amplifolius, P. bicupulatus, P. clystocarpus, P. confervoides, P. crispus, P. diversifolius, P. epihydrus, P. floridanus, P. foliosus, P. friesii, P. gramineus, P. groenlandicus, P. hillii, P. illinoensis, P. natans, P. nodosus, P. oakesianus, P. oblongus, P. obtusifolius, P. ogdenii, P. perfoliatus, P. praelongus, P. pulcher, P. pusillus, P. richardsonii, P. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
P. alpinus, P. amplifolius, P. bicupulatus, P. clystocarpus, P. confervoides, P. crispus, P. epihydrus, P. floridanus, P. foliosus, P. friesii, P. gramineus, P. groenlandicus, P. hillii, P. illinoensis, P. natans, P. nodosus, P. oakesianus, P. oblongus, P. obtusifolius, P. ogdenii, P. perfoliatus, P. praelongus, P. pulcher, P. pusillus, P. richardsonii, P. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
Synonyms P. alpinus subsp. tenuifolius, P. alpinus var. subellipticus, P. alpinus var. tenuifolius, P. tenuifolius, P. tenuifolius var. subellipticus P. capillaceus
Name authority Balbis: Misc. Bot. 13. (1804) Rafinesque: Medical Repository hexade 2, 5:354. (1808)
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