Dense-flowered cordgrass

Spartina densiflora

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  • Erect grey-green stems, 1 to 5 feet tall.
  • Spike-like collection of small flowers, 2­1/2 to 12 in.
  • S. densiflora foliage is more grey and grows in compact bunches, compared to native S. foliosa. S. densiflora also blooms up to a month earlier.
  • See also the entry for smooth cordgrass, Spartina alterniflora.
Identification key (with photos) at: San Francisco Estuary Invasive Spartina Project web site (

Identification key in: Hickman, J. ed. 1993. The Jepson Manual: Higher Plants of California. University of California Press.

Growth and spread

  • Can spread from fragments of root or underground stem, often transported with tides. Seeds can float and may also be transported with tides (Faber 2000).
  • Once established, plants spread laterally by vegetative shoots (Faber 2000).

Habitat and local distribution

  • Middle to high tidal zone of salt marshes.
  • Native to Chile, first established in California in Humbolt county, later introduced to Marin County in a wetlands restoration project.
  • Currently S. densiflora is found along Corte Madera Creek, and across the Bay at Point Pinole.

For maps of distribution, refer to


  • Grows higher in tidal range than native plant, potentially replacing natives such as alkali heath, Jaumea, and western marsh rosemary, and pickleweed (Faber 2000; Grossinger et al. 1998).

Prevention and Control


  • Plant S. foliosa in disturbed tidal marsh areas.
  • Search threatened areas regularly (at least annually) to look for newly arrived plants.

General control notes

  • A large-scale invasive Spartina control project for San Francisco Bay and Delta was in process as this guide was published. In upcoming years this effort should produce the best control information for the region. Check the Invasive Spartina Project web site (address below) regularly.
  • There is little information on control methods for dense-flowered cordgrass (Faber 2000). Control methods for smooth cordgrass should be applicable and are detailed below.

Manual or mechanical control

(Daehler 2000)

  • Hand pulling—effective for small infestations and in soft substrates; underground stems (rhizomes) must also be removed.
  • Estimated costs: vary depending on if volunteers conduct removal and on the plant density (Gibbons et al. 1999). There may be additional fees for disposal of plant material.
  • Solarization—mow stems and cover with geotextile fabric or heavy-duty black plastic; covering must be well secured; most effective if covered for one or more years.

Biological control

  • Biological control agents—none have been approved by USDA; probably not a viable method due to potential risk to native California cordgrass (Daehler 2000).

Chemical control

  • Application of herbicides—2 to 5% glyphosate (Rodeo®) along with a surfactant recommended by hand spraying; apply at low tide for maximum exposure; more than one application may be necessary; only Rodeo® registered for use in estuarine wetlands (Daehler 2000).
  • Estimated costs: costs for materials and application by a contractor are approximately $250 per acre for glyphosate, depending on size of treatment area, scale of treatment, and herbicide dosage. It is recommended to contract a licensed professional for herbicide applications (Gibbons et al. 1999).

References and more information

Faber, P. 2000. Spartina densiflora. In Invasive Plants of California Wildlands. Carla C. Bossard, John M. Randall, Marc C. Hoshovsky, Editors. University of California Press. Available at's_Wildlands .

Gibbons, M.V., M.G. Rosenkranz, H.L. Gibbons, Jr., and M.D. Sytsma. 1999. Guide for Developing Integrated Aquatic Vegetation Management in Oregon. Center for Lakes and Reservoirs, Portland State University, Portland, OR.

Grossinger, R., J. Alexander, A. Cohen, and J. Collins. 1998. Introduced Tidal Marsh Plants in the San Francisco Estuary: Regional Distribution and Priorities for Control. San Francisco Estuary Institute, Oakland California.

San Francisco Estuary Invasive Spartina Project web site ( Contents of site includes species ID sheets, invasion impacts, distribution maps, control program information, project documents, and related web sites.

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