Maryland Department of Natural Resources

​Learning Resources

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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​

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​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:Water Starwort

Scientific Name:Callitriche spp.

Native or Non-native:Native


Illustration:Links to Water Starwort collage


Link to larger illustration:
​Click here for larger image.
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Printable Version:
Print out a copy for the field.

Family:Callichtrichaceae

Distribution:
Water starworts are widespread, usually in very shallow, quiet non-tidal fresh waters, and are found in all 49 continental states. Water starworts can also be found occasionally in protected tidal waters.

Recognition:
​ Water starworts are small plants with very bright green leaves. The leaves are obovate to oval in shape and are 2 cm long and 3 to 8 mm wide. When it grows on mud in low-water conditions, the leaves of water starwort are oblong. Upper leaves of the plants are obovate to oval and are often floating or emergent. The genus Callitriche also includes one terrestrial species (C. deflexa).

Ecological Significance:
​Water starwort provides important habitat for small reptiles and amphibians, as well as a spawning platform for fish. It also provides a food source for waterfowl through its leaves and berries. May cause problems if too much is growing in an area by crowding out other plants and causing shade in the water which makes it hard to grow under.

Similar Species:
When underwater and without flowers or seeds, the water starworts can resemble common waterweed (Elodea canadensis). Water starwort, however, has only two leaves at each joint whereas the leaves of common waterweed grow in whorls of 3.

Reproduction:
​Flowering occurs in July to September. Very small indistinct flowers grow together in groups of 1 to 3, without perianth, in the axils of leaves; these form numerous seeds closely set within the leaf axils.
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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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