Stems branched, especially distally, terete to slightly compressed, to 75 cm. Leaves: those of main stem only slightly larger than those of branches; stipules with stipular sheaths not inflated, 0.8--1.1 cm, ligule 0.8 mm; blade linear, 5.6--9.2 cm ´ 0.2--1 mm, apex acute to mucronate or apiculate; veins 1--3. Inflorescences: peduncles terminal or axillary, erect to ascending, cylindric, 4.5--11.4 cm; spikes moniliform to cylindric, 14--22 mm; verticels 3--5. Fruits yellow-brown to brown, oblanceoloid, 3.8--4 ´ 2.5--3.1 mm; beak toward abaxial margin, erect, 0.5--1.1 mm. 2n = 78. Flowering summer--fall. Brackish to alkaline waters of lakes, streams, rivers, and estuaries; 0--2400 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Fla., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico; Central America; South America; Eurasia; Australia. No specimens have been seen from Delaware, but the species is to be expected there. The sago-pondweed is among the most important species as food for waterfowl (E. Moore 1913). The species reproduces vegetatively by underground tubers and is spread by various duck species, especially canvas backs. In a study of food for ducks, a population of canvas backs was observed feeding in aquatic vegetation comprised of several genera, including sago-pondweed. When the stomach contents were examined, they were found to contain essentially 100% tubers of sago-pondweed (E. Moore 1913).
Two hybrids with this species as a putative parent have been described under the genus Potamogeton. These are P. pectinatus ´ P. vaginatus (= P. ´ bottnicus Hagström) and P. filiformis ´ P. pectinatus (= P. ´ suecicus K. Richter).
Perennial submersed aquatic herb with slender rhizomes 30 cm - 0.75 m tall Stem: unbranched or sparsely branched below with elongate internodes. Freely branched above with 1 - 3 cm long internodes. Leaves: submersed, alternate, stalkless, opaque, 3 - 10 cm long, 0.5 - 1.5 mm wide, linear with a tapering base and pointed tip (sometimes with a short, abrupt tip), one- to three-veined, channeled, plump. Stipules adhered to base of leaf blade for two-thirds or more their length, 8 - 11 mm long. In quiet waters the leaves retain their characteristic fan-like clusters, but in flowing water they change dramatically, being 1 - 1.5 mm wide and losing their fan-like quality due to an elongated stem. Inflorescence: an upright to ascending, bead-like to cylindrical spike with three to five whorls of flowers, submersed, 1 - 4 cm long, on an axillary or terminal stalk. Stalk cylindrical, 3 - 10 cm long, flexible. Flowers: greenish, tiny. Stamens four. Anthers two-chambered, with four edge-to-edge sepal-like outgrowths. Pistils four. Fruit: an achene, yellowish brown to brown, 3 - 4.5 mm long, 2.5 - 3 mm wide, obliquely reverse egg-shaped, rounded along the back, plump, sometimes keeled, with an upright, 0.5 - 1 mm long beak.
Similar species: Pondweeds in the genus Potamogeton are similar to those of Stuckenia, but the submersed leaves of Potamogeton are translucent, flat, and lack channels, whereas those of Stuckenia are opaque, channeled, and plump. Compare the stipule sheaths of this species with the inflated ones of S. vaginatus to best distinguish between the two.
Flowering: late May to early September
Habitat and ecology: Very common in lakes, often in calcareous waters.
Occurence in the Chicago region: native
Notes: These plants are a very important food source for waterfowl, especially ducks.
Etymology: Pectinatus means comb-like.
Author: The Morton Arboretum
FNA 2000, Cronquist et al. 1977
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Wholly submerged with branched stems, terete to slightly compressed to 75 cm in length, arising from slender creeping rhizome. Leaves: All submersed and only slightly larger than branches, stipules not inflated adnate to base of leaf and forming a slender clasping sheath around stem, sheath 2-3 cm long, greenish, blade filiform 2-12 cm long, less than 1 mm wide, apex acute to mucronate or apiculate, with 1-3 veins. Flowers: Terminal and axillary spike on very slender peduncle 1-15 cm long, spike 1-3 cm long with 2-6 unequally spaced whorls of flowers, lower ones up to 1 cm apart, upper ones more crowded, flowers small, with brownish green tepals 1-1.5 mm long, very short style. Fruits: Obliquely ovoid achene, 2.5-4 mm long, 2-3.5 mm wide, dorsal keel low and rounded. Ecology: Found in shallow ponds, streams, and lakes from 1,000-8,000 ft (305-2438 m); flowers July-September. Distribution: Throughout much of the world, on every continent; throughout N. Amer.; in every state in the US and throughout CAN, south to S. Amer. Notes: Distinguished by the open stipule sheath that is fused to the blade for most of its length. Ethnobotany: Unknown Etymology: Stuckenia is named for the German botanist Wilhelm Adolf Stucken (1860-1901), while pectinata means comb-like. Synonyms: Coleogeton pectinatus, Potamogeton pectinatus, Stuckenia pectinatus Editor: SBuckley 2010, FSCoburn 2015
Stems 3-8 dm, simple or sparingly branched below with elongate internodes, above usually flexuous, freely dichotomously branched, with internodes 1-3 cm; rhizome slender, ending in a white tuber 1-1.5 cm; lvs all submersed, narrowly linear, 3-10 cm נ0.5-
1.5 mm, 1-nerved, tapering to an acute tip; stipular sheaths adnate to the blade and rather closely clasping the stem for 1-3 cm, the margins connate at least below, the free tip 2-10 mm; spikes submersed and
hydrophilous, 1-4 cm, on peduncles 3-10 cm, with several whorls of fls, the lower separated; frs obliquely obovoid, 3-4.5 mm, distinctly short-beaked, rounded on the back, with a low dorsal keel only, or with 2 lateral keels only, or with 3 keels; 2n=78. Calcareous or alkaline, usually shallow water; nearly cosmopolitan, and widespread in our range. A major food for ducks.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.