Reservoirs, Lakes and Ponds

Illinois Pondweed | Potamogeton illinoensis

Potamogeton pusillus L.: Narrowleaf pondweed, small pondweed, baby pondweed. Potamogetonaceae (pondweed family). Native perennial/annual. Growing submersed, from fibrous roots, or rarely very slender rhizomes, in ponds and streams. Has numerous submersed leaves of a single shape; there are no floating leaves. The slender, sometimes flattened, much-branching stems are held erect underwater, to 3.3 ft (1 m). Leaves are alternate, narrow, ribbon- or grass-like, slightly pointed, 0.4 - 2.75 in (1 - 7 cm) long, with very slender leaf stalks. A prominent midvein is found on the lower side of the blade; one or more pairs of parallel side veins are seen. Two tiny glands, visible as hard round yellow dots, are at the base of the leaf or stipule. Stipules are thin, membrane-like, making a half- to completely-open tube around base of leaf; 0.7 in (1.7 cm) long, they wear away with age. Flower spike stalks are slender to thread-like. Plant can produce winter buds. Grows in mixed stands of plants that may cause water use/access problems.