Spartina alterniflora - Loisel.
Saltwater Cordgrass
Other English Common Names: Saltmarsh Cordgrass, Smooth Cordgrass
Other Common Names: smooth cordgrass
Taxonomic Status: Accepted
Related ITIS Name(s): Spartina alterniflora Loisel. (TSN 41267)
Unique Identifier: ELEMENT_GLOBAL.2.150874
Element Code: PMPOA5S010
Informal Taxonomy: Plants, Vascular - Flowering Plants - Grass Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Poaceae Spartina
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Spartina alterniflora
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 13May2016
Global Status Last Changed: 06Sep1984
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Nation: United States
National Status: N5
Nation: Canada
National Status: N5 (19Nov2017)

U.S. & Canada State/Province Status
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United States Alabama (SNR), California (SNR), Connecticut (SNR), Delaware (S5), Florida (SNR), Georgia (SNR), Louisiana (SNR), Maine (SNR), Maryland (SNR), Massachusetts (SNR), Mississippi (SNR), New Hampshire (SNR), New Jersey (S5), New York (S5), North Carolina (S5), Rhode Island (SNR), South Carolina (SNR), Texas (SNR), Virginia (S5), Washington (SNR)
Canada Labrador (S1S2), New Brunswick (S5), Newfoundland Island (S2), Nova Scotia (S5), Prince Edward Island (S5), Quebec (S4S5)

Other Statuses

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Distribution
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U.S. States and Canadian Provinces

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NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States AL, CA, CT, DE, FL, GA, LA, MA, MD, ME, MS, NC, NH, NJ, NY, RI, SC, TX, VA, WA
Canada LB, NB, NF, NS, PE, QC

Range Map
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Ecology & Life History Not yet assessed
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Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High
Rounded I-Rank: High
I-Rank Reasons Summary: Spartina alterniflora is native to the East and Gulf coasts of North America, where it is a dominant component of low salt marsh communities. However, on the Pacific coast, particularly in some of the bays in Washington and California, this species is having substantial negative impacts on native biodiversity. Impacts in California (San Francisco Bay) are predominantly attributable to hybrids between S. alterniflora and the native (California endemic) S. foliosa; this evaluation encompasses the impact on biodiversity of both pure S. alterniflora and S. alterniflora x S. foliosa hybrids, as these two taxa are difficult to distinguish in the field. S. alterniflora invades open mudflats, S. foliosa-dominated marsh, higher marsh dominated by Salicornia virginica, and associated drainage sloughs. Invasion increases sediment accretion, alters marsh and coastline hydrology, and impacts nutrient cycling through increased deposition of detritus. Significant structural changes occur when S. alterniflora invades open mudflats, dramatically changing food web structure and reducing foraging habitat for resident shorebirds, wading birds, and waterfowl, birds migrating along the Pacific flyway, and fish and shellfish populations. Invasion of vegetated marsh habitats results in significant structural and community changes. Hybridization between S. alterniflora and S. foliosa produces very vigorous plants which could ultimately lead to the extirpation of pure S. foliosa. Invaded habitats host several endangered species. Currently established in 6 major estuaries in Washington, Oregon, and California; an additional 25 Pacific estuaries are believed invasible. Dispersal of seeds and vegetative fragments occurs on the tides. Local expansion in Washington and California is proceeding rapidly. Eradication efforts via biological control (WA only) and other control methods are underway, but management is complicated by the plant's vegetative reproduction abilities and the difficulties of accessing and working in the soft mudflat environments.
Subrank I - Ecological Impact: High
Subrank II - Current Distribution/Abundance: High
Subrank III - Trend in Distribution/Abundance: High/Medium
Subrank IV - Management Difficulty: Medium
I-Rank Review Date: 24Sep2007
Evaluator: Gravuer, K.
Native anywhere in the U.S?
Native Range: Native to the Atlantic and Gulf Coasts of North America, including New Brunswick, Newfoundland, Nova Scotia, Prince Edward Island, eastern Quebec, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, southeastern New York, New Jersey, Delaware, Maryland, eastern Virginia, eastern North Carolina, South Carolina, southeastern Georgia, Florida, southern Alabama, southern Mississippi, southern Louisiana, and Texas. Also native to Guadeloupe and Trinidad in the Caribbean, and to eastern South America, including French Guiana, Guyana, Suriname, eastern Brazil, Uruguay, and Argentina (Buenos Aires and Rio Negro) (USDA-ARS 2007).

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: This species is a non-native that is established outside of cultivation (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: Invaded habitats include open mudflats or sandflats, California cordgrass (S. foliosa)-dominated marsh, higher marsh dominated by Salicornia virginica, and drainage sloughs associated with these habitats (Daehler 2000, DiTomaso and Healy 2003).

Subrank I - Ecological Impact: High

1. Impact on Ecosystem Processes and System-wide Parameters:High significance
Comments: Increases sediment accretion and alters marsh and coastline hydrology. The rigid, densely packed stems decrease the rate of tidal flow, causing suspended sediment to precipitate, while dense root mats trap sediment (Daehler and Strong 1996). Increased rates of sediment accretion raise the substrate elevation, clog natural channels and sloughs, widen the floodplain of tidal rivers and channels, and create steeper beach profiles (Daehler and Strong 1996, Grevstad et al. 2003, Western Aquatic Plant Management Society 2004). Coastlines are altered from gently-sloping mud flats with shallow tidal channels to marshes with steeply sloping seaward edges and deep, steep-sided tidal channels (Western Aquatic Plant Management Society 2004). Increased sediment accretion may change water circulation patterns (Western Aquatic Plant Management Society 2004). Also impacts nutrient cycling by dramatically increasing the amount of detritus (Western Aquatic Plant Management Society 2004). Although S. alterniflora is a native and important component of salt marshes on the East and Gulf Coast of North America, fundamental differences in the physical setting and evolved ecological communities and food webs on the West Coast mean that the invasion of S. alterniflora causes significant changes in the structure, function, and composition of West Coast sites (Western Aquatic Plant Management Society 2004, Levin et al. 2006).

2. Impact on Ecological Community Structure:High significance
Comments: Invades intertidal mud flats, marsh areas dominated by native Spartina foliosa (in California), and high marsh vegetation dominated by Salicornia virginica. The most severe structural changes occur in the intertidal mudflats, where formerly open expanses of intertidal mud are transformed into dense monocultures of this species (and its hybrids) (Daehler 2000, Flora of North America Editorial Committee 2003, Grevstad et al. 2003, Ayres et al. 2004). In the S. foliosa zone in California, a change in dominance to S. alterniflora and hybrids increases the height and density of grass (DiTomaso and Healy 2003). Significant vegetation density and cover changes also occur when this species invades Salicornia virginica high marsh habitat; wrack may also smother Salicornia and Distichlis, creating bare patches (Ayres et al. 2004).

3. Impact on Ecological Community Composition:High significance
Comments: Hybridizes with the native Spartina foliosa in California; many of the hybrids have greater fitness, competitive ability, and ecological amplitude than either parent species (Ayres and Strong 2003), resulting in the complete or near-complete replacement of S. foliosa by hybrids at many sites (Ayres et al. 2004). Also competitively displaces some areas of higher marsh vegetation dominated by Salicornia virginica (Calloway and Josselyn 1992 cited in Ayres et al. 2004). Invades and dominates marsh restoration projects (Ayres et al. 2004). Changes caused by S. alterniflora invasion have significant impacts on animal species throughout the coastal food web. Resident and migratory shorebirds, wading birds, and waterfowl that forage in open mud flat habitats generally will not forage in the dense Spartina stands, resulting in lost feeding grounds (Daehler and Strong 1996). In the Willapa National Wildlife Refuge, S. alterniflora has displaced an estimated 16 to 20 percent of critical habitat for wintering and breeding aquatic birds (Western Aquatic Plant Management Society 2004). Along the Pacific flyway, estuaries are limited and declining, and reduced shorebird feeding areas might lead to a decline in populations of many migratory birds (Ayres et al. 2004, Levin et al. 2006). Fish that forage in the shallow waters of the tidal mudflats, including juvenile chum and Chinook salmon, and native shellfish that depend on mud flat habitats are also likely to be adversely affected (Simenstad and Thom 1995 cited in Grevstad et al. 2003). Essentially, invaded systems shift from an algae-based to a detritus-based food web, resulting in differences in biomass and trophic structure of benthic communities, and a loss of key trophic support for fishes and birds (Levin et al. 2006).

4. Impact on Individual Native Plant or Animal Species:High significance
Comments: Hybridizes freely with the native S. foliosa in California throughout the range of their co-occurrence. Hybrids have a suite of characters (reproductive and ecological vigor, tidally-dispersed seed) that is expected to drive their rapid spread and ultimately could lead to extinction of pure S. foliosa (Ayres and Strong 2003).

5. Conservation Significance of the Communities and Native Species Threatened:High significance
Comments: Native Pacific estuarine communities are ecologically unique (Daehler and Strong 1996). Along the Pacific flyway, estuaries are limited and declining; remaining feeding grounds are therefore of high significance to the persistence of migratory shorebirds (Ayres et al. 2004, Levin et al. 2006). Invasion occurs with the foraging and nesting habitat of the Federally and state endangered California clapper rail (Rallus longirostris obsoletus); impacts on the rail are generally assumed to be negative (ISSG 2005), although preferred nesting habitat may actually be created by the invasion (Daehler and Strong 1996). The endangered salt marsh harvest mouse (Reithrodontomys raviventris) and the endangered soft birds-beak (Cordylanthus mollis ssp. mollis) depend on high marsh habitat dominated by Salicornia virginica and will likely be negatively impacted (Ayres et al. 2004, ISSG 2005). Invasion could also preclude the reintroduction and recovery of endangered California Sea-Blight (Suaeda californica) in San Francisco Bay by invading its critical habitat, open intertidal foreshores (P. Baye pers. comm. cited in Ayres et al. 2004).

Subrank II. Current Distribution and Abundance: High

6. Current Range Size in Nation:Moderate significance
Comments: Native to the East and Gulf Coasts of North America, but introduced to and invading Pacific Coast estuaries. Washington: Willapa Bay (Pacific County); Copalis River estuary and Damon Point (Grays Harbor County); and areas of Puget Sound and the Strait of Juan de Fuca, including Sequim Bay (Clallam County), Thorndyke Bay and Kala Point (Jefferson County), and Padilla Bay (Skagit County) (Western Aquatic Plant Management Society 2004). Oregon: Suislaw River Estuary (Western Aquatic Plant Management Society 2004). California: San Francisco Bay from Point Pinole (San Pablo Bay) south to the sloughs of the South Bay (mostly represented by hybrids; little pure S. alterniflora exists in San Francisco Bay) (Ayres et al. 2004). Populations at Humboldt Bay have been eradicated (DiTomaso and Healy 2003). For range size evaluation, the area of interest was defined as the Pacific coast.

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:High significance
Comments: Significant impacts have been described in both Washington and California, throughout the invaded areas (Western Aquatic Plant Management Society 2004, Ayres et al. 2004). No information was available from Oregon.

8. Proportion of Nation's Biogeographic Units Invaded:High/Moderate significance
Comments: Approximately 2 out of 4 potentially invasible ecoregions are invaded, based on visual comparison of the generalized range and ecoregions map (The Nature Conservancy 2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Medium/Low significance
Comments: Invades coastal or bayside intertidal zones with saline or brackish water, sometimes expanding up tidal rivers/creeks (Daehler 2000, Western Aquatic Plant Management Society 2004). Invaded habitats include open mudflats or sandflats, California cordgrass (S. foliosa)-dominated marsh, higher marsh dominated by Salicornia virginica, and drainage sloughs associated with these habitats (Daehler 2000, DiTomaso and Healy 2003). Can colonize a broad range of substrates, from sand and silt to loose cobble, clay, and gravel (Western Aquatic Plant Management Society 2004, Elkhorn Slough Foundation 2007). Can tolerate a wide range of environmental conditions, including inundation up to 12 hours a day, pH levels from 4.5 to 8.5, and salinity from 10 to 60 ppt (Western Aquatic Plant Management Society 2004, Brusati 2006). Can grow from mean high water to approximately 1 meter from mean low water (ISSG 2005). Found in areas of low to moderate wave energy; does not grow on wave-swept Pacific coast beaches (Daehler 2000, Western Aquatic Plant Management Society 2004).

Subrank III. Trend in Distribution and Abundance: High/Medium

10. Current Trend in Total Range within Nation:Moderate significance
Comments: S. alterniflora was intentionally planted in nearly all the Bays were it is currently known to be established, with the exception of Willapa Bay, WA where introduction (by humans) was unintentional (Western Aquatic Plant Management Society 2004). However, the species has apparently spread on its own from Willapa Bay, WA to Grays Harbor, WA (30 km) (Daehler and Strong 1996). In addition, spread by hybrids to different areas within San Francisco Bay is apparently occurring unassisted (Ayres et al. 2004). In 2001, isolated hybrid plants were discovered in outer coast estuaries north of the Bay, at Bolinas Lagoon and at Drakes Estero at Pt. Reyes National Seashore, CA (Ayres et al. 2004).

11. Proportion of Potential Range Currently Occupied:High/Moderate significance
Comments: Believed to be capable of invading 31 estuary sites along the Pacific coast, of which it has already invaded 6 (Daehler and Strong 1996). In San Francisco Bay, the gross invaded area is estimated to be < 8%, and net invaded acreage to be < 1%, of the potentially invasible area (Ayres et al. 2004). Although S. alterniflora was intentionally planted in nearly all the Bays were it is currently known to be established, researchers believe that it is capable of colonizing as-yet uninvaded estuaries by tidal seed dispersal (Ayers et al. 2004).

12. Long-distance Dispersal Potential within Nation:Moderate significance
Comments: S. alterniflora was intentionally planted in nearly all the Bays were it is currently known to be established, for the purpose of salt marsh restoration and erosion control (Daehler 2000, Ayers et al. 2004, Western Aquatic Plant Management Society 2004). However, this introduction route is no longer operating, as the plant is widely perceived as problematic (Ayres 2004). Seed and clonal fragments float on the tide (Daehler 2000, Ayers et al. 2004, Western Aquatic Plant Management Society 2004). Seeds can also be spread long distances by floating on racks of dead Spartina stems in the fall (Brusati 2006). Vegetative fragments may break off from established plants on eroding banks of tidal sloughs, and/or during winter storms (Daehler 2000, Brusati 2006). Such long-distance dispersal has been observed to occur occasionally. For example, natural dispersal appears to have occurred from Willapa Bay to Gray's Harbor, WA and from San Francisco Bay populations to outer coast estuaries north of the Bay (Ayers et al. 2004).

13. Local Range Expansion or Change in Abundance:High/Moderate significance
Comments: Within San Francisco Bay, hybrids have increased in area 100-fold since the 1970s, with the rate of expansion ranging from constant (exponential increase in area) to increasing through time (greater than exponential increase in area) (Ayres et al. 2004). In a recent study, large numbers of hybrids were found at restored marshes in the East Bay which were colonized mainly by tidally borne seed (Ayres et al. 2004). Very rapid rates of hybrid spread (e.g. 2.5-fold in 1 year, 8-fold in 3 years) have been documented within some parts of San Francisco Bay (Ayres et al. 2004). Invasion is also proceeding rapidly in Willapa Bay, WA; between 1988 and 1992, the species invaded 800 ha of open mud to cover a total of 1000 ha (Daehler and Strong 1996), and aerial photographs document a 60% increase in cover between 1994 and 1997 (Reeves 1999 cited in Grevstad et al. 2003).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:High/Moderate significance
Comments: At least hybrids are apparently capable of invading intact marsh habitats (Ayres 2004). Disturbance does seem to promote rapid establishment, however; for example, tidally-borne hybrid seed rapidly colonized open mud of newly restored marshes in east San Francisco Bay (Ayres et al. 2004). S. alterniflora is able to rapidly colonize bare areas (Western Aquatic Plant Management Society 2004).

15. Similar Habitats Invaded Elsewhere:Low significance
Comments: Established in Australia, New Zealand, India, China, France, the Netherlands, and the United Kingdom (Normile 2004, ISSG 2005, USDA-ARS 2007), apparently in similar habitats.

16. Reproductive Characteristics:High significance
Comments: Reproduces by clonal expansion, vegetative fragmentation, and seed production (Western Aquatic Plant Management Society 2004). Produces few or no seeds in many areas where it has been introduced; low soil temperature can delay or suppress flowering and reduce seed production, and self-pollinated seeds (i.e. those in isolated patches) often fail to germinate (Western Aquatic Plant Management Society 2004). However, many hybrid plants are self-fertile (Ayres 2004). Conversely, seed production in some situations can be prodigious; for example, the output of one hybrid plant in San Francisco Bay was 4.9 million fertile seeds (Zaremba 2001 cited in Ayres et al. 2004). Overwinter seed survival can be low due to winter storms and burial by algae (Daehler 2000). Seeds are short-lived (8 months - 1 year) and do not tolerate desiccation, so the species does not have a persistent seed bank (Daehler 2000, Western Aquatic Plant Management Society 2004). Vegetative fragments can be spread year round at sites prone to erosion (Daehler 2000).

Subrank IV. General Management Difficulty: Medium

17. General Management Difficulty:Moderate significance
Comments: Seedlings can be pulled out, but pulling or digging established clones is not effective. Covering small clones with woven geotextile fabric can be suitable for small infestations. Mowing can be effective, but clones must be mowed repeatedly - larger clones need to be mowed nine to ten times over two seasons for eradication. Success of control with glyphosate + surfactant or with imazapyr varies depending on the conditions of the application, but success can be achieved with this method (Western Aquatic Plant Management Society 2004, Brusati 2006). For application of glyphosate + surfactant, costs for materials and application by a contractor are approximately $250 per acre. Treatments often need to be reapplied to keep infestations from rebounding (Patten 2002 cited in Grevstad et al. 2003). The planthopper Prokelisia marginata has been introduced into Willapa Bay, Washington for biological control; preliminary results are somewhat encouraging (Grevstad et al. 2003). In San Francisco Bay, P. marginata is already present as an accidental introduction, but plants in San Francisco Bay have proven to be resistant to it. Biological control is an unlikely option in California because S. foliosa would also likely be impacted (Brusati 2006). To date there have been no successful eradications of large infestations, although attempts are in progress in Willapa Bay and San Francisco Bay (Daehler 2000).

18. Minimum Time Commitment:Moderate significance
Comments: Seeds are short-lived (8 months - 1 year) and do not tolerate desiccation, so the species does not have a persistent seed bank (Daehler 2000, Western Aquatic Plant Management Society 2004). However, the species' vigorous vegetative reproduction capabilities mean that control treatments often need to be reapplied to keep infestations from rebounding (Patten 2002 cited in Grevstad et al. 2003).

19. Impacts of Management on Native Species:Medium/Low significance
Comments: Many commonly-used treatments are likely to impact co-occurring natives, because treatment is applied at the patch level (e.g. covering with geotextile fabric) or is severe, given the tenacity of these plants. However, if the biological control program in Washington proves successful, impacts on co-occurring natives there may be minimal (Grevstad et al. 2003).

20. Accessibility of Invaded Areas:High/Moderate significance
Comments: Some patches are inaccessible by foot and must be treated by boat or air (Daehler 2000). Control is difficult and dangerous in soft mud flats (ISSG 2005).
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References
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  • Ayres, D. 2004. Part IV. Plant Assessment Form, for use with "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands" by the California Exotic Pest Plant Council and the Southwest Vegetation Management Association: Spartina alterniflora x foliosa hybrids, S. alterniflora Lois. Available: http://portal.cal-ipc.org/files/PAFs/Spartina%20alterniflora%20hybrids.pdf (Accessed 2007).

  • Ayres, D. R. and D. R. Strong. 2003. Spartina foliosa (Poaceae) - a common species on the road to rarity? Madroņo 50(3): 209-213.

  • Ayres, D. R., D. L. Smith, K. Zaremba, S. Klohr, and D. R. Strong. 2004. Spread of exotic cordgrasses and hybrids (Spartina sp.) in the tidal marshes of San Francisco Bay, California, USA. Biological Invasions 6: 221-231.

  • Brusati, E. 2006. Fact Sheet: Smooth cordgrass (Spartina alterniflora). Plant Conservation Alliance's Alien Plant Working Group. Online. Available: http://www.nps.gov/plants/alien/fact/pdf/spal1.pdf (Accessed 2007).

  • Daehler, C. C. 2000. Spartina alterniflora Loisel. pgs. 296-299 in Bossard, C.C., J.M. Randall, and M. Hoshovsky. (eds.) Invasive Plants of California's Wildlands. University of California Press, Berkeley, CA.

  • Daehler, C. C. and D. R. Strong. 1996. Status, prediction, and prevention of introduced cordgrass Spartina spp. invasions in Pacific estuaries, USA. Biological Conservation 78: 51-58.

  • DiTomaso, J.M. and E.A. Healy. 2003. Aquatic and riparian weeds of the West. Regents of University of California, Division of Agriculture and Natural Resources, Publication 3421.

  • Elkhorn Slough Foundation. 2007. Least wanted aquatic invaders: Smooth cordgrass (Spartina alterniflora). Elkhorn Slough National Estuarine Research Reserve. Online. Available: http://www.elkhornslough.org/research/aquaticinvaders/aquatic3.htm (Accessed 2007).

  • Flora of North America Editorial Committee. 2003a. Flora of North America North of Mexico. Vol. 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford Univ. Press, New York. xxv + 781 pp.

  • Grevstad, F. S., D. R. Strong, D. Garcia-Rossi, R. W. Switzer, and M. S. Wecker. 2003. Biological control of Spartina alterniflora in Willapa Bay, Washington using the planthopper Prokelisia marginata: agent specificity and early results. Biological Control 27: 32-42.

  • Invasive Species Specialist Group (ISSG). 2005. Global Invasive Species Database. Online. Available: http://www.issg.org/database (Accessed 2006).

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Levin, L. A., C. Neira, and E. D. Grosholz. 2006. Invasive cordgrass modifies wetland trophic function. Ecology 87(2): 419-432.

  • Normile, D. 2004. Expanding trade with China creates ecological backlash. Science 306: 968-969.

  • USDA, ARS, National Genetic Resources Program. 2005. December 9 last update. Germplasm Resources Information Network (GRIN) Online Database. National Germplasm Resources Laboratory, Beltsville, Maryland. Available: http://www.ars-grin.gov2/cgi-bin/npgs/html/index.pl (Accessed 2006).

  • USDA, ARS, National Genetic Resources Program. 2007 last update. Germplasm Resources Information Network (GRIN). National Germplasm Resources Laboratory, Beltsville, MD. Online. Available: http://www.ars-grin.gov/cgi-bin/npgs/html/index.pl (Accessed 2007).

  • Western Aquatic Plant Management Society. 2004, 16 June last update. Spartina alterniflora - smooth cordgrass - A problem aquatic plant in the western USA. Online. Available: http://www.wapms.org/plants/spartina.html (Accessed 2007)

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