Stuckenia filiformis
Stuckenia striata
fineleaf pondweed, slender-leaf pondweed, thread-leaf false pondweed, thread-leaf pondweed, western pondweed
broadleaf pondweed, Nevada-pondweed, striped pondweed
freely branching proximally, sparsely branching distally, subterete, (10–)20–60(–100) cm.
branched distally, terete to 5-ridged, to 200 cm.
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 2 times or more those on branches;
stipules with stipular sheaths not inflated, 1.2–3.4 cm, ligule 0.2–1.1 cm;
blade linear, 5–21 cm × 0.4–5.1 (–8.5) mm, apex apiculate, cuspidate, or rarely round;
veins 3–5.
peduncles terminal, erect, filiform to slender, 2–10(–15) cm;
spikes cylindric to moniliform, 5–55 mm;
verticels 2–6(–9).
peduncles axillary, rarely terminal, erect to ascending, cylindric, 1.2–5.2 cm;
spikes cylindric, rarely moniliform, 13–45 mm;
verticels 4–9.
dark brown, obovoid, 2–3 × 1.5–2.4 mm;
beak inconspicuous.
brown to reddish brown, obovoid to oblanceoloid, 3–3.9 × 2.8–3 mm;
beak toward abaxial margin, erect or rarely recurved to apex, 0.2–0.3 mm.
apparently unknown.not available.
Stuckenia filiformis
Stuckenia striata
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.)
Stuckenia striata is widespread, although not common, in the western United States, extending southward into Argentina and Chile. Potamogeton latifolius [no combination in Stuckenia has been proposed] was accepted by R. F. Thorne (1993b). After examining specimens throughout the range and studying dozens of populations in the field, we have determined that the two names represent the same taxon. We are placing P. latifolius in synonymy.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Plants 20–100 cm; stipules on proximal portion of stem inflated, disintegrating with age; fruits often absent. | subsp. occidentalis |
1. Plants 10–30 cm; stipules on proximal portion of stem tightly clasping or slightly enlarged, persistent; fruits common. | → 2 |
2. Peduncles Peduncles with flowers and/or fruits 4 cm or more apart; leaves 0.2–0.5 mm wide. | subsp. Filiformis |
2. Peduncles with flowers and/or fruits less than 4 cm apart; leaves to 1 mm widee. | subsp. alpina |
BC
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WA
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Flora NW
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MI Flora
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