Sago Pondweed is also known as fennel-leaf pondweed or Potamogeton pectinatus. The genus Potamogeton is one of the largest and most diverse groups of aquatic plants, all of which are commonly called pondweeds by botanists.Throughout the world there are about 80-90 different pondweed species, approximately 20 of which occur in the northwest. Sago pondweed can be found in many lakes and rivers throughout Washington. It seems to occur mostly in low- to - mid-elevation lakes with moderate to high levels of nutrients. It also is tolerant of hard water lakes, like some of those in the central part of the state
Sago pondweed is one of the thin-leaved pondweeds. This group of pondweeds is usually dreaded by aquatic plant specialists who care about telling the different species apart. Pondweeds, especially the thin-leaved kind, are a notoriously difficult group to distinguish from each other. Luckily, sago pondweed is relatively distinctive.
Its thin leaves are submersed and all alike (many other types of pondweeds have floating leaves as well as submersed ones). They are threadlike, one-to-five inches long by less than 1/16 inch wide. They come off a sheath surrounding the main stem at a distinctive angle which gives the plants a fan-like appearance. Small flowers are produced in whorls around the stem and are also submersed. The seeds are plump, about 1/8 inch long, and often float near the water's surface on the stem. Sago pondweed will also reproduce from sprouts along spreading roots (rhizomes). These rhizomes produce small tubers which help the plant to overwinter.
Sago pondweed is considered a pest in some parts of the world. It can become quite thick in shallow waterways, and since it spreads via rhizomes and seeds, it has a high capacity to reproduce. It is considered to be a major pest plant in eastern Washington irrigation canals and ditches. However, in Washington lakes and rivers it is usually found as part of a diverse, healthy plant community. It is a valuable food plant for wildlife, particularly waterfowl. Diving ducks rely on the tubers as a food source, and many dabbling ducks will eat the foliage and seeds. Sago pondweed, as part of a diverse aquatic plant community, also provides valuable habitat for small invertebrates and young fish who forage among its branches and use its dense growth to hide from predators.
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