Sago Pondweed
Stuckenia pectinata
Pondweed family (Potamogetonaceae)

Description: This perennial plant is a submerged aquatic about 1-3' long. There is more branching of the stems above than below, creating fan-like aggregations of leaves. The stems are up to 1.0 mm. across, light green to nearly white, terete to slightly compressed (flattened), and hairless; they are slender and flexible. The slender leaves are 1-5" long, up to 1.0 mm. across, and mostly alternate; they are filiform, medium green to olive-green, hairless, and toothless, tapering to acute tips. The leaves are highly flexible and readily bend. At the leaf bases along the stems, there are sheath-like stipules about -1" long and up to 1.0 mm. across; these stipules are connate (wrapping tightly around the stems) below, but they become free toward their tips.

Individual spikes of flowers are produced occasionally from the axils of the leaves and the tips of outer stems on peduncles about 1-8" long. These floral spikes are -1" long, consisting of 2-6 interrupted clusters of flowers. Each greenish white flower is about 1/8" across, consisting of 4 tepals with abruptly tapered bases, 4 stamens, and a pistil with a short style. The stalk of each floral spike is light green to reddish purple, terete, and hairless. Both the floral spikes and peduncles complete their development underwater. The blooming period can occur from late spring to early fall. The submerged flowers are cross-pollinated via water. Afterwards, fertile flowers are replaced by plump achenes about 3-4 mm. long and 2.5-3.0 mm. across. These achenes are obovoid-globoid in shape and slightly compressed with small beaks at their apices. The root system is fibrous, rhizomatous, and tuberous. Clonal colonies of plants are often produced from the rhizomes.

Cultivation: The preference is full sun, shallow water up to 4' deep, and a mucky bottom. Clear water that is somewhat alkaline and calcareous is preferred, but this plant adapts to a variety of conditions, including brackish water.

Range & Habitat: The native Sago Pondweed is occasional in northern and central Illinois, becoming uncommon or absent in the southern section of the state (see Distribution Map). This aquatic plant is also found in Eurasia. Habitats include quiet inlets of lakes, ponds, reservoirs, drainage canals, and creeks with slow currents. Sometimes, Sago Pondweed becomes the dominant aquatic plant in these habitats, forming extensive colonies.

Faunal Associations: Submerged aquatic pondweeds are an important source of food for both waterfowl (swans, geese, & ducks) and omnivorous turtles. These animals eat the foliage and/or seeds. Sago Pondweed is one of the more valuable pondweeds for waterfowl, in particular, because its root system produces edible tubers. Examples of waterfowl that feed on this aquatic plant include the Trumpeter Swan, Canvasback, Redhead, Wood Duck, and Ruddy Duck; see the Wetland Bird Table for a more complete listing of these species. Turtles that feed on pondweeds include the Snapping Turtle, Blanding's Turtle, Musk Turtle (or Stinkpot), Painted Turtle, Slider, Ouachita Map Turtle, and False Map Turtle. Muskrats also feed on the tubers and foliage. Sago Pondweed provides good cover for fish and other kinds of aquatic wildlife.

Photographic Location: This plant was found in the shallow water of a pond in Champaign, Illinois.

Comments: This plant is often referred to as Potamogeton pectinatus. Two common names that are in use include Fennel-Leaf Pondweed and Comb Pondweed. The long slender leaves of Sago Pondweed tend to form dense fan-like aggregations that lie a little below the water surface. Other submerged aquatic pondweeds (Potamogeton spp.) tend to have leaves that are wider (exceeding 1.0 mm. in width) or shorter (never longer than 3" in length) and they are usually less densely aggregated. Two boreal species of the same genus, Stuckenia filiformis (Slender-Leaved Pondweed) and Stuckenia vaginata (Sheathing Pondweed), are similar to Sago Pondweed, but they have not been found in Illinois. These latter two species differ from Sago Pondweed by having 1) leaves that are sometimes wider than 1.0 mm. across, 2) leaves with obtuse tips, 3) outer stems that are less abundantly branched, and 4) achenes with either smaller beaks or no beaks.