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 1½-5"
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
½-1½" long and up to 1.0 mm. across; these stipules are connate
(wrapping tightly around the stems) below, but they become free toward
Individual spikes of flowers are produced occasionally from the
axils of the leaves and the tips of outer stems on peduncles about
1½-8" long. These floral spikes are ½-1½" 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
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
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
preference is full sun, shallow water up to 4' deep, and a mucky
bottom. Clear water that is somewhat alkaline and calcareous is
but this plant adapts to a variety of conditions, including brackish
The native Sago Pondweed is
occasional in northern and central Illinois, becoming uncommon or
absent in the southern section of the state (see Distribution
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.
Submerged aquatic pondweeds are an important
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.
This plant was found in the shallow water of a
pond in Champaign, Illinois.
This plant is often referred to as Potamogeton
. 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
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,
(Slender-Leaved Pondweed) and Stuckenia vaginata
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.