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narrowleaf pondweed, potamot à feuilles raides, stiff-leaf pondweed, straight-leaf pondweed

cinnamonspot pondweed, potamot oblong

Cauline stems

terete, without spots, 27–95 cm;

glands white, green, greenish brown, or gold, to 0.3 mm diam.

terete, without spots, 5–30 cm;

nodal glands absent.

Turions

terminal or lateral, common, 2.5–4.8 cm × 0.8–2.2 mm, soft;

leaves ± 2-ranked, flattened with outer and inner leaves in same plane;

outer leaves 3–4 per side, base not corrugate, or rarely corrugate, apex acute;

inner leaves undifferentiated.

absent.

Leaves

submersed, ± spirally arranged, rigid, sessile;

stipules disintegrating, inconspicuous, connate, free from blade, white, not ligulate, 0.6–1.6 cm, fibrous, shredding at tip, apex obtuse;

blade green to olive-green, linear, not arcuate, 1.2–6.3 cm × 0.6–2 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute to nearly bristle-tipped, rarely obtuse to apiculate, lacunae absent;

veins 3–5(–7).

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

Floating leaves

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

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;

peduncles not dimorphic, terminal, erect, rarely recurved, cylindric, rarely slightly clavate, 1–4.5 cm;

spike not dimorphic, cylindric, 0.6–1.3 cm.

unbranched, emersed;

peduncles not dimorphic, erect to slightly recurved, cylindric, 4–12 cm;

spikes not dimorphic, cylindric, 20–40 mm.

Fruits

sessile, green-brown, ovoid, turgid, not abaxially or laterally keeled, 1.9–2.1 × 1.3–1.8 mm;

beak erect, 0.5–0.8 mm;

sides without basal tubercles;

embryo with 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)

absent.

present.

2n

= 26.

= 26.

Potamogeton strictifolius

Potamogeton oblongus

Phenology Flowering and fruiting summer–fall. Flowering July–August.
Habitat Alkaline waters of lakes and slow-moving streams Acid to neutral waters of ponds, lakes, and occasionally streams
Elevation 50–2000 m (200–6600 ft) 10–100 m (0–300 ft)
Distribution
from FNA
CT; IL; IN; MA; ME; MI; MN; ND; NE; NY; OH; PA; SD; UT; VA; VT; WI; WY; AB; MB; NB; ON; QC; SK; YT
[WildflowerSearch map]
[BONAP county map]
from FNA
NF; NS; SPM; Europe; n Africa; Atlantic Islands (Azores) [Introduced in North America]
[BONAP county map]
Discussion

Potamogeton strictifolius is a relatively uncommon species found in alkaline waters. Fairly rigid leaves of the species make floating onto paper unnecessary in the collecting process. The leaves have a tendency to become revolute during the growing season. The species superficially resembles several other species of linear-leaved pondweeds. Consequently, many specimens of this species have been misidentified as other species and vice versa. Thus, literature records are often suspect.

One hybrid, Potamogeton strictifolius × P. zosteriformis (= P. × haynesii Hellquist & G. E. Crow), has been described.

(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. alpinus, 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. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
P. alpinus, 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. 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. strictifolius var. rutiloides
Name authority A. Bennett: J. Bot. 40: 148. (1902) Viviani: Annali di Botanica 1(2): 102. (1802)
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