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​

 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.
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Common Name:  
or
Scientific Name:


Common Name:False Loosestrife

Scientific Name:Ludwigia sp.

Native or Non-native:Native


Illustration:False Loosestrife photo collage


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

Printable Version:
Print out a copy for the field.

Family:Onagraceae

Distribution:
Common on the Coastal Plain and occasionally throughout Chesapeake Bay along the shores of freshwater streams, rivers and ponds. This plant is located in other parts of the USA as well, with the highest concentration in the Midwestern states. This is an emergent terrestrial plant, but one that can grow underwater for many weeks and is thus often confused for SAV.

Recognition:
Grows to 1 meter tall, leaves usually linear to lanceolate 1 to 6 cm long, alternate or opposite. The stems are light green to pink, and are generally sparsely branched towards the bottom. Flowers July to September and produces flowers that are light green to pink with 4 lobes and up to 4 petals. Petals are not often present, but when they are they are green/greenish yellow and 1-2mm in length. The most distinctive part of the plant are its fruits which have four sides and four sepals at the top of each fruit.

Ecological Significance:
The flowers provide nectar and pollen to insects, and the leaves of the plant are fed on by other insects.

Similar Species:
None

Reproduction:
Reproduces by seed. The flowers can self-pollinate if no insects aid in the pollination process, and then the fruits are split open containing many very small seeds, which are blown by the wind or carried by water.
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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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