Submerged Aquatic Vegetation (SAV) Identification Key

​​The bay grass key was designed to allow you to identify most species of bay grasses found in Maryland. Although bay grasses are notoriously difficult to identify using standard taxonomic keys, the flexible format of the Internet allows us to combine detailed pictures, simple line drawings and text messages in a stepwise sequence that makes identifying bay grasses simple. You may find it useful to have a clear metric ruler with millimeters marked, a magnifying glass, and a Ziploc plastic bag to help you in the process of identifying your plant.

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Common Name:  
Scientific Name:

Common Name:Sago Pondweed

Scientific Name:Stuckenia pectinata*

Native or Non-native:Native

Illustration:Sago Pondweed collage

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Sago pondweed is widely distributed in the United States, South America, Europe, Africa and Japan. In the Chesapeake Bay sago pondweed is widespread, growing in fresh non-tidal to moderately brackish waters as well as in some lakes. It can tolerate high alkalinity and grows on silty-muddy sediments. It tolerates strong currents and wave action better than most bay grasses because of its long rhizomes and rhizomes and runners.

Thread-like leaves are 3 to 10 cm (1 ¼ in to 4 in) long, and 0.5 to 2 mm (1/32 in to 1/16 in) wide, and taper to a point. The basal sheath of leaves sometimes has a pointed tip or bayonet that aids in identification when plants are not in flower. Seeds form in terminal clusters. Stems are slender, and abundantly branched so that bushy leaf clusters fan out at the water surface. Roots have slender rhizomes, and are long and straight.

Ecological Significance:
Sago pondweed (* formerly Potamogeton pectinatus) is widespread throughout the United States and is considered one of the most valuable food sources for waterfowl in North America. Its nutrient filled seeds and tubers, as well as leaves, stems and roots, are consumed by numerous species of ducks, geese, swans and marsh and shorebirds. Sago pondweed beds are also excellent fish habitats.

Similar Species:
Horned pondweed (Zanichellia palustris) and widgeon grass (Ruppia maritima) have a very similar appearance to sago pondweed and are difficult to identify without fruits. Sago pondweed has alternately arranged leaves, but horned pondweed has oppositely arranged or whorled leaves. The leaves of widgeon grass are also alternately arranged but are not in bushy clusters like those of sago pondweed. The seeds are also distinctly different among the three species. Sago pondweed seeds are in terminal clusters. Widgeon grass has single seed pods that form at the base of fan-shaped clusters of short stalks, and horned pondweed seeds occur in groups of 2-4, are horn-shaped pairs and form in the leaf axils.

Reproduction is by seed formation and asexual reproduction. Sexual reproduction occurs during early summer by formation of a spike of perfect flowers that appear like beads on the slender stalk. Flowers release pollen that floats on the water surface, resulting in fertilization. Developing seeds remain on the rachis of the spike until autumn when they are dispersed into the water. The germination rate is low, however, and asexual reproduction is more significant. Asexual reproduction is by two kinds of starchy tubers: 1) tubers produced at ends of underground rhizomes and runners, or 2) another tuber that forms in leaf axils and at end of leaf shoots; these later sink to the substrate. Both kinds of tubers grow singularly or in pairs, and can form plants later in spring.

Print out a complete version of the key in PDF format (Adobe Acrobat file 18MB)

For permission to reproduce individual photos, please contact Mike Naylor

The text and photos used in this key were produced through a collaborative effort among the following partners.

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