Stuckenia filiformis |
Stuckenia vaginata |
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fineleaf pondweed, slender-leaf pondweed, thread-leaf false pondweed, thread-leaf pondweed, western pondweed |
bigsheath-pondweed, potamot engainé, sheath pondweed, sheathing pondweed |
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Stems | freely branching proximally, sparsely branching distally, subterete, (10–)20–60(–100) cm. |
freely branching proximally to distally, terete, 20–50(–70) cm. |
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Leaves | length and width of those on main stem only slightly larger than those on branches; stipules with stipular sheaths often inflated on proximal portion of stem, 1–4(–9.5) cm, summit of midstem stipules tight to stem, ca. ± same width as stem, ligule 2–20 mm, distinct, especially on distal stipules; blade filiform or slenderly linear, 1–15 cm × 0.2–2(–3.7) mm, apex notched, blunt, or short-apiculate; veins 1–3. |
length and width of those on main stem only slightly larger than those on branches; stipules with stipular sheaths inflated 3–5 times stem thickness, 2–9 cm, ligule absent, obscure, or to 0.2 mm; blade narrowly filiform to linear, 1–10(–15) cm × 0.2–2.9 mm, apex rounded, obtuse, or slightly notched; veins 1(–3). |
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Inflorescences | peduncles terminal, erect, filiform to slender, 2–10(–15) cm; spikes cylindric to moniliform, 5–55 mm; verticels 2–6(–9). |
peduncles terminal, erect, slender, 3–15 cm; spikes moniliform, 10–80 mm; verticels 3–12. |
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Fruits | dark brown, obovoid, 2–3 × 1.5–2.4 mm; beak inconspicuous. |
brown, obliquely obovoid, 3–3.8 mm × 2–2.9 mm; beak inconspicuous. |
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2n | = 78. |
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Stuckenia filiformis |
Stuckenia vaginata |
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Phenology | Flowering late summer–fall. | |||||||||
Habitat | Deep lakes and ponds | |||||||||
Elevation | 0–2300 m (0–7500 ft) | |||||||||
Distribution |
AK; AZ; CA; CO; IA; ID; ME; MI; MN; MT; ND; NE; NH; NJ; NM; NV; NY; OH; OR; PA; SD; UT; VT; WA; WI; WY; AB; BC; MB; NB; NS; NT; NU; ON; PE; QC; SK; YT; nearly worldwide
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AK; CO; ID; MN; MT; ND; OR; SD; UT; WA; WI; WY; AB; BC; MB; NT; NU; ON; QC; SK; YT; Eurasia
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Discussion | Three distinct subspecies seemingly apparently occur in North America. They are separated mainly by the size of the plants and the peduncle characteristics. Stuckenia filiformis subsp. occidentalis typically grows in cold deep water, standing or with a strong current. This variety tends to become robust and is easily confused with Stuckenia vaginata and S. striata. Stuckenia filiformis subsp. alpina is a much smaller plant typically growing in standing waters. Stuckenia filiformis subsp. filiformis is restricted to the far north. In the intermountain region of western United States is a more robust form that is quite similar to S. filiformis subsp. alpina but although it has previously been recognized as Potamogeton [Stuckenia] filiformis var. macounii Morong (J. L. Reveal 1977b). Subspecies ca. 5 (3 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
One hybrid, P. pectinatus × P. vaginatus (= P. × bottnicus Hagström), with this species as a putative parent has been described under the genus Potamogeton. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 22. | FNA vol. 22. | ||||||||
Parent taxa | Potamogetonaceae > Stuckenia | Potamogetonaceae > Stuckenia | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Potamogeton filiformis | Potamogeton vaginatus | ||||||||
Name authority | (Persoon) Börner: Flora fur das deutsche Volk 713. (1912) | (Turczaninow) Holub: Folia Geobot. Phytotax. 19: 215. (1984) | ||||||||
Web links |