Spartina alterniflora, Smooth Cordgrass

Gardens & Landscapes, Invasive Species, Extension Master Gardener October 20, 2015 Print Friendly and PDF

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.

cordgrass cordgrass
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.

smooth cordgrass smooth cordgrass
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.

smooth cordgrass  
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.

 
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

California cordgrass California cordgrass
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


 

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.