Invasive Species: Spartina alterniflora, Smooth Cordgrass
Smooth cordgrass is a perennial grass that is native to the Atlantic and Gulf Coasts of North America but is invasive along the Pacific Coast. Hollow stems grow from 2 to 4 ft (0.6 to 1.2 m) tall. Leaves are 8 to 20 in. (20 to 50 cm) long and 1 to 8 in. (2.5 to 20 cm) wide and are often purplish at the base. Total plant height can be up to 7 feet tall. Flowering occurs in July to November, when densely packed clusters of tan flowers develop. The fruit are flattened and smooth, with pointed tips. The plant also expands via underground rhizomes. Smooth cordgrass was introduced on the West Coast in the early 1970s to be used as erosion control. It can hybridize with other spartina species. Plants have now become extremely invasive in salt marshes along the West Coast.
What are invasive species, and why should we be concerned about them?
Taxonomy: Scientific and Common Names for This Species
Cyperales > Poaceae > Spartina alterniflora Loisel.
Synonym(s): Atlantic cordgrass, saltmarsh cordgrass
Spartina alterniflora – USDA PLANTS Profile
Distribution Maps
smooth cordgrass – The reported distribution of this invasive species across the United States (Source: Invasive Plant Atlas of the United States)
Up-to-the-minute distribution maps and why they are important
Reporting This Invasive Species
What is the best way to report the occurrence of an invasive species?
How to report an invasive species sighting to EDDMapS – Early Detection & Distribution Mapping System
EDDMapS – Report an invasive species to EDDMapS.
County Extension Offices – Find your county Extension office on this map provided by USDA.
How to Identify
This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.
Grass
Smooth cordgrass is a perennial grass with hollow stems that grow from 2 to 4 ft (0.6 to 1.2 m) tall.
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| Joseph M. DiTomaso, University of California – Davis, bugwood.org | Joseph M. DiTomaso, University of California – Davis, bugwood.org |
Foliage
Leaves are 8 to 20 in. (20 to 50 cm) long and 1 to 8 in. (2.5 to 20 cm) wide and are often purplish at the base.
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| John M. Randall, The Nature Conservancy, bugwood.org | Joseph M. DiTomaso, University of California – Davis, bugwood.org |
Flower
Flowering occurs in July to November, when densely packed clusters of tan flowers develop.
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| Joseph M. DiTomaso, University of California – Davis, bugwood.org | bugwood.org |
Fruit
The fruit are flattened and smooth, with pointed tips. The plant also expands via underground rhizomes.
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| USDA PLANTS Database, USDA NRCS PLANTS Database, bugwood.org | bugwood.org |
Native Spartina Species Resemble Smooth Cordgrass
Spartina foliosa, California cordgrass – Images at invasive.org
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| Joseph M. DiTomaso, University of California – Davis, bugwood.org | Joseph M. DiTomaso, University of California – Davis, bugwood.org |
Additional Images for Smooth Cordgrass
smooth cordgrass – Images at invasive.org
Learning Resources for Smooth Cordgrass
Invasive Spartina Project: Field Guide – California Coastal Conservancy
Identifying Spartina Grass: Video – Reflections on the Water
Additional Information, Biology, Control and Management Resources
Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state’s land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.
United States Land-Grant University System – Find your Land-Grant University’s College of Agriculture, University Cooperative Extension Service, or other related partner on this map provided by USDA.
Weeds Gone Wild: Alien Plant Invaders of Natural Areas – Plant Conservation Alliance
Invasive Spartina Project – California Coastal Conservancy
Plant Info and Images – University of Florida, Center for Aquatic and Invasive Plants
Plant Profiles – California Invasive Plant Council
Alaska Natural Heritage Program – University of Alaska, Anchorage
Fire Effects Information System – USDA Forest Service
Marine Invasive Species – National Park Service