Submerged Aquatic Vegetation (SAV) Identification Key
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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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If you already know the identity of a particular bay grass use the drop down boxes below. |
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Common Name:
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Scientific Name:
| | Common Name: | Curly Pondweed |
| | Scientific Name: | Potamogeton crispus |
| | Native or Non-native: | Non-native
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| | Link to larger illustration: | |
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| | Family: | Potamogetonaceae |
| | Distribution: | Curly pondweed grows in fresh non-tidal to slightly brackish tidal waters, as well as in lakes and ponds. Curly pondweed is native to Eurasia, Africa, and Australia and is believed to have been introduced to the Americas in the late 1800’s. Today curly pondweed has worldwide distribution and is widely distributed in streams, rivers and reservoirs of the Chesapeake Bay. |
| | Recognition: |
Perhaps the most easily recognizable species in the bay, with robust leaves 3 cm to 10 cm (1 ¼ in to 4 in) long, broad, linear and finely toothed, with undulated (curly) margins. Leaves are arranged alternately or slightly opposite on flattened, branched stems. Roots and rhizomes are shallow, and not as extensive as in other bay grasses. Vegetative buds sprout in the fall and the winter form of the plant develops with blue-green leaves that are more flattened. In spring, the spring/summer form appears with reddish-brown leaves that are wider and curlier. Flowering occurs in late spring or early summer and the plants begin to die-off after the vegetative buds are produced. The buds remain dormant until fall, when the cycle is repeated. |
| | Ecological Significance: | Curly pondweed is an introduced species that is widespread throughout the U.S. While not normally problematic in tidal waters, curly pondweed can be invasive when it occurs in lakes and reservoirs. Curly pondweed provides food for ducks and is particularly valuable winter and spring habitat for fish and invertebrates due to its ability to grow when waters are too cool for many other aquatic plants. |
| | Similar Species: | Curly pondweed may resemble young shoots of redhead grass (Potamogeton perfoliatus), but the leaves of redhead grass are typically shorter and wider. |
| | Reproduction: |
Plants reproduce through extension of rhizomes, development of burr-like asexual structures near stem tips, and by seed development from flowers that float at water surface atop spikes. The curly pondweed life-cycle has a three-stages: winter form, spring/summer form, and dormant vegetative (asexual) bud. |
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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.
