Maryland Department of Natural Resources

​Learning Resources

​​​

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.

​I don't know the species​

 Use the SAV Key
​I know the species
 ​If you already know the identity of a particular bay grass use the drop down boxes below.
​​

Common Name:  
or
Scientific Name:


Common Name:Pondweeds

Scientific Name:Potamogeton sp.

Native or Non-native:Native


Illustration:Pondweeds photo


Link to larger illustration:
​Click here for larger image.
Click here for more images.​​


Printable Version:
Print out a copy for the field.

Family: Potamogetonaceae

Distribution:
Cosmopolitan throughout MD in rivers, ponds, reservoirs and tidal freshwater to moderately brackish tributaries of Chesapeake Bay. Pictured is P. spirillus, one of the smallest of the Chesapeake Bay pondweeds.Some other pondweed species found in Maryland are Horned Pondweed (Zannichellia palustris), Curly Pondweed (Potamogeton crispus), Sago Pondweed (Stuckenia pectinata), Slender Pondweed(Potamogeton pusillus), and Illinois Pondweed (Potamogeton illinoensis).

Recognition:
Range in size from 0.1 to 2 meters tall, with leaves from 1 to 15 cm long. Most species have bimorphic leaves (two distinctly different leaf shapes on a single plant) and these leaves are arranged in an alternate, whorled, or opposite fashion going along the stem. Many species of pondweeds are extremely difficult to identify even for experts.

Ecological Significance:
Many species of pondweeds provide a food source for waterfowl, and as habitat and cover for fish and other aquatic organisms. Pondweeds are probably the most abundant non-tidal SAV found in the mid-Atlantic.

Similar Species:
This depends on the type of pondweed being observed. There are many different types with various distinct features.

Reproduction:
Primarily sexual reproduction by seed.
​


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.

SAV Key Sponsor Logos