Stuckenia filiformis

(Persoon) Börner

Flora fur das deutsche Volk 713. 1912.

Common names: Threadleaf-pondweed
Basionym: Potamogeton filiformis Persoon Syn. Pl. 1: 152. 1805
Treatment appears in FNA Volume 22.

Stems freely branching proximally, sparsely branching distally, subterete, (10–) 20–60 (–100) cm. 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. Inflorescences: peduncles terminal, erect, filiform to slender, 2–10 (–15) cm; spikes cylindric to moniliform, 5–55 mm; verticels 2–6 (–9). Fruits dark-brown, obovoid, 2–3 × 1.5–2.4 mm; beak inconspicuous.

Distribution

V22 233-distribution-map.jpg

Alta., B.C., Man., N.B., N.S., N.W.T., Nunavut, Ont., P.E.I., Que., Sask., Yukon, Alaska, Ariz., Calif., Colo., Idaho, Iowa, Maine, Mich., Minn., Mont., N.Dak., N.H., N.J., N.Mex., N.Y., Nebr., Nev., Ohio, Oreg., Pa., S.Dak., Utah, Vt., Wash., Wis., Wyo., nearly worldwide

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).

Selected References

None.

Key

1 Plants 20–100 cm; stipules on proximal portion of stem inflated, disintegrating with age; fruits often absent. Stuckenia filiformis 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. Stuckenia filiformis subsp. Filiformis
2 Peduncles with flowers and/or fruits less than 4 cm apart; leaves to 1 mm widee. Stuckenia filiformis subsp. alpina

"not elongating" is not a number.

... more about "Stuckenia filiformis"
short-apiculate +, blunt +  and notched +
Robert R. Haynes +  and C. Barre Hellquist +
(Persoon) Börner +
Potamogeton filiformis +
inconspicuous +
0.2 cm2 mm <br />0.002 m <br /> (0.37 cm3.7 mm <br />0.0037 m <br />) +
1 cm10 mm <br />0.01 m <br /> (15 cm150 mm <br />0.15 m <br />) +
linear;filiform +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Threadleaf-pondweed +
Alta. +, B.C. +, Man. +, N.B. +, N.S. +, N.W.T. +, Nunavut +, Ont. +, P.E.I. +, Que. +, Sask. +, Yukon +, Alaska +, Ariz. +, Calif. +, Colo. +, Idaho +, Iowa +, Maine +, Mich. +, Minn. +, Mont. +, N.Dak. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, Nebr. +, Nev. +, Ohio +, Oreg. +, Pa. +, S.Dak. +, Utah +, Vt. +, Wash. +, Wis. +, Wyo. +  and nearly worldwide +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
obovoid +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.24 cm2.4 mm <br />0.0024 m <br />) +
axillary +  and terminal +
cylindric +  and capitate +
submersed +
acute +, turgid +  and channeled +
0.2 cm2 mm <br />0.002 m <br /> (?) +  and 2 cm20 mm <br />0.02 m <br /> (?) +
orthotropous +
not pedunculate +
not spiraling +
10 cm100 mm <br />0.1 m <br /> (15 cm150 mm <br />0.15 m <br />) +
2 cm20 mm <br />0.02 m <br /> (10 cm100 mm <br />0.1 m <br />) +
short-stipitate +  and stipitate +
Flora fur das deutsche Volk +
auriculate +  and not auriculate +
not persisting +
inflated +
cylindric +  and moniliform +
0.5 cm5 mm <br />0.005 m <br /> (5.5 cm55 mm <br />0.055 m <br />) +
epitepalous +
60 cm600 mm <br />0.6 m <br /> (100 cm1,000 mm <br />1 m <br />) +
subterete +
20 cm200 mm <br />0.2 m <br /> (60 cm600 mm <br />0.6 m <br />) +
4 cm40 mm <br />0.04 m <br /> (9.5 cm95 mm <br />0.095 m <br />) +
not tubular +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
Coleogeton +
Stuckenia filiformis +
Stuckenia +
species +
1 (?) +  and 3 (?) +
caulescent +, not rhizomatous +  and rhizomatous +
annual +  and perennial +