Potamogeton alpinus
Potamogeton crispus
alpine pondweed, northern pondweed, potamot alpin, reddish pondweed
crisp-leaf pondweed, crispate leaf pondweed, curled pondweed, curly pondweed, curly-leaf pondweed, potamot crepu
terete, without spots, to 200 cm;
nodal glands absent.
flattened, without spots, to 100 cm;
nodal glands absent.
absent.
common, axillary or terminal, 1.5–3 × ca. 2 cm, hard;
leaves ± 2-ranked;
outer leaves 1–4 per side, base not corrugate, apex rounded;
inner leaves rolled into linear, terete structure, oriented parallel to outer leaves.
submersed and floating or floating absent, ± spirally arranged.
submersed, ± spirally arranged, sessile, lax;
stipules persistent to deliquescent, inconspicuous, convolute, free from blade, brownish, not ligulate, to 0.5 cm, not fibrous, not shredding at tip, apex obtuse;
blade light to dark green, linear, not arcuate, 1.2–9 cm × 4–10 mm, base obtuse to rounded, without basal lobes, not clasping to nearly clasping, margins conspicuously serrate, not crispate, apex not hoodlike, round to round-acute, lacunae in 2–5 rows each side of midrib;
veins 3–5.
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).
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.
unbranched, emersed;
peduncles not dimorphic, terminal or axillary, erect, cylindric, 3–10(–16) cm;
spikes not dimorphic, cylindric, 10–35 mm.
unbranched, emersed;
peduncles not dimorphic, terminal or rarely axillary, erect to ascending, cylindric, 2.5–4 cm;
spikes not dimorphic, cylindric, 10–15 mm.
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, red to reddish brown, obovoid, turgid to slightly concave, not abaxially or laterally keeled, 6 × 2.5 mm;
beak apically recurved, 2–3 mm;
sides without basal tubercles;
embryo with 1 full spiral.
present.
absent.
= 52.
= 52 (Europe).
Potamogeton alpinus
Potamogeton crispus
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.)
No specimens have been seen from New Brunswick, but the species is to be expected there.
Potamogeton crispus, an introduced species, has spread throughout much of North America. The expansion of this species’s range from its original collection in North America, apparently about 1840, has been discussed (R. L. Stuckey 1979). This is the only species of pondweeds in North America with serrate leaves and consequently it is easily recognized.
Life history of Potamogeton crispus is unusual as it flowers and fruits in late spring and early summer, at which time it also produces turions. The plants decay shortly after those structures develop, leaving only fruits and turions, which survive the summer. No one has observed any seed germination, but the turions (referred to as dormant apices) germinate in late summer or fall, and the plants overwinter as small plants only a few cm centimeters in size, even under the ice in northern climates (R. L. Stuckey et al. 1978). Growth then continues as the water begins warming in the spring.
One hybrid, Potamogeton crispus × P. praelongus (= P. × undulatus Wolfgang ex Schultes & Schultes f.), has been described.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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