History in the United States
In its native range, decomposed smooth cordgrass provides an important source of food for crabs and other invertebrates and cordgrass marshes are nursery grounds for juvenile fishes and blue crabs. However, these species do not occur on the west coast and smooth cordgrass does not appear to serve the same functions in its non-native invaded habitats. Smooth cordgrass was introduced to Washington State in the late 1800s, either in shipments of oysters from the east coast or as packing material in ships’ cargo. It was introduced to San Francisco Bay in the 1970s as part of a project to stabilize the bay shoreline.
Spartina alterniflora is a smooth cordgrass that is commonly found in marshes. Its two forms (tall and short) naturally exist along the Atlantic coast of North and South America (Adam 1990; Bertness 1985). The grass has stiff stems with long and narrow leaves. The flowering portion of the plant is spike-like and can be up to 30 cm long (Wan 2009). It inhabits salt marsh habitats which are known for their anoxic, nutrient limited, and high salinity conditions (Adam 1993). Spartina alterniflora competes with Spartina patens, Juncus gerardi, and Distichlis spicata and the delineation between species appears to be due to both physical stress and nutrient limitation (Levine 1998). S. alterniflora ameliorates the environment and allows for other species to grow and flourish, such as the algae Ascophyllum nodosum and Haleobia australis (hydroboid snails) (Gerard 1999; Canepuccia 2007). In addition to facilitating the growth of organisms indirectly as an ecosystem engineer, S. alterniflora also plays a direct role as a food source for some organisms, although Spartina usually does not experience much herbivory. One consumer of S. alterniflora is the periwinkle snail, Littoraria irrorata, which forms wounds on the leaves and facilitates fungal growth, which is then harvested (Silliman & Newell 2003). Planthoppers, Prokelsia marginata and Prokelsia dolus specialize on Spartina and are found to coexist on Spartina throughout the north east of the United States (Denno et. al. 2000). Grasshoppers are also found to graze on S. alterniflora, with species varying according to lattitude (Pennings and Silliman 2005). Additionally, wild horses appear to prefer grazing on S. alternifora over D. spicata (Furbish 1994).
S. alterniflora provides numerous ecosystem services. These include protection from storm surges, capturing sediment, and filtering pollutants (Maricle 2002; Wan 2009). It is for these reasons that S. alterniflora has been transplanted worldwide. In China, S. alterniflora has been invaluable in storm surge protection and prevention of damages, as well as in land reclamation and filtration of pollutants (Wan 2009). S. alterniflora reproduces by two main routes: clonal reproduction by the formation of underground rhizomes and sexual reproduction by flowers to form seeds (Metcalfe et al. 1986; Trilla et.al. 2009). This makes S. alterniflora a formidable invader, quickly overtaking bare mud flats when introduced to new areas. There are downsides to the spread of S. alterniflora as well. In some locations S. alterniflora outcompetes native Suaeda, a seepweed or seablite, which draws tourists for the “Red Beach” it creates (Wan 2009). This eliminated the “Red Beach” landscape, thus deteriorating levels of tourism (Wan 2009). Competition between S. alterniflora and scrubby mangrove has also been noted, with S. alterniflora being the stronger competitor (Wan 2009).
Adam, P. 1990. Plants and Salinity in Salt Marsh Ecology. Cambridge University Press, New York, New York, USA.
Bertness, M. D.1985. Fiddler crab regulation of Spartina alterniflora production on a New England salt marsh. Ecology. 66:1042–1055.
Canepuccia, A. D., M. Escapa, P. Daleo, J. Alberti, F. Botto, and O. O. Iribarne. 2007. Positive interactions of the smooth cordgrass Spartina alterniflora on the mud snail Heleobia australis, in South Western Atlantic salt marshes. Journal of Experimental Marine Biology and Ecology. 353:180–190.
Denno, R.F., M.A. Peterson, C. Gratton, J. Cheng, et. al. 2000. Feeding-induced changes in plant quality mediate interspecific competition between sap-feeding herbivores. Ecology. 81:1814-1827.
Furbish, C.E., and M. Albano. 1994. Selective herbivory and plant community structure in a mid-Atlantic salt marsh. Ecology. 75:1015-1022.
Gerard, V. A. 1999. Positive interactions between cordgrass, Spartina alterniflora, and the brown alga, Ascophyllum nodosum ecad scorpioides, in a mid-Atlantic coast salt marsh. Journal of Experimental Marine Biology and Ecology. 239:157–164.
Levine, J.M., J.S. Brewer, and M.D. Bertness. 1998. Nutrients, competition and plant zonation in a New England salt marsh. Journal of Ecology. 86:285-292.
Maricle, B. R., and R. W. Lee. 2002. Aerenchyma developoment and oxygen transport in the estuarine cordgrasses Spartina alterniflora and S. anglica. Aquatic Botan.y 74:109–120.
Metcalfe, W.Scott; Ellison, Aaron M.; Bertness, M. D. 1986. Survivorship and spatial development of Spartina alterniflora Loisel. (Gramineae) seedlings in a New England salt marsh. Annals of Botan.y 58:249–258.
Pennings, S.C. and B. R. Silliman. 2005. Linking biogeography and community ecology: latitudinal variation in plant-herbivore interaction strength. Ecology. 86: 2310-2319.
Silliman, B.R., and S.Y. Newell. 2003. Fungal farming in a snail. Proceedings of the National Academy of Sciences, USA. 100:15643-15648.
Trilla, G. G., P. Kandus, V. Negrin, R. Vicari, and J. Marcovecchio. 2009. Tiller dynamic and production on a SW Atlantic Spartina alterniflora marsh. Estuarine, Coastal and Shelf Science. 85:126–133.
Wan, S., P., Qin, J. Liu, and H. Zhou. 2009. The positive and negative effects of exotic Spartina alterniflora in China. Ecological Engineering. 35:444–452.
General: Smooth cordgrass is a herbaceous, native, warm season grass that forms dense vegetative colonies along shorelines and inter-tidal flats in coastal wetlands. Smooth cordgrass is a robust, rapidly spreading plant, tolerant to fluctuating water depths and salinity. Smooth cordgrass spreads primarily by vegetative propagation, producing new stems from an extensive system of underground rhizomes. Plant height will vary according to site conditions, but generally will range from 24” to 72.” Colonies tend to grow parallel to and continuous along shorelines; the width and thickness of a vegetative colony is controlled by a number of site-specific conditions such as elevation, shoreline-slope, and frequency, depth, and duration of flooding.
Distribution: Generally, this species occurs in the coastal states along the U.S. It is not native on the West Coast. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
saltmarsh cordgrass, oystergrass, saltwater cordgrass
Regularity: Regularly occurring
Regularity: Regularly occurring
Occurrence in North America
NH NY NC RI SC TX VA WA NF PQ
from Newfoundland and Quebec to northern Florida, and in the Gulf of
Mexico from Florida to southern Texas [24,27]. It is also found along
the coast in Washington .
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
1 Northern Pacific Border
Distribution in the United States
Along the eastern seaboard and the Gulf coast, smooth cordgrass is the dominant native plant in salt marshes. However, it is introduced and considered invasive in Gray’s Harbor, Puget Sound, and Willapa Bay, Washington; the Suislaw River estuary, Oregon; and San Francisco Bay, California. Most of the invasive cordgrass in California is actually the hybrid with California cordgrass; little pure smooth cordgrass exists in San Francisco Bay.
Smooth cordgrass is a large, coarse, warm-season grass, which is
physiologically adapted to the salt marsh habitat [26,27]. Plants
growing under good conditions reach 8 feet (2.5 m) tall, while those
growing in the high salt marshes, especially at edges of salt pans, may
be only 16 inches (40 cm) tall, including the inflorescence . A
dense stand of this tall grass is like a small forest of dark green
plants. Almost no light gets through to the mud beneath the stand.
Tidal currents are strong where the best growth occurs and wash away
dead leaves, leaving stands clean and free of debris most of the year
Smooth cordgrass is a tall clumping perennial grass with creeping rhizomes that grows up to 7 ft. in height. The leaves have flat blades 12 to 20 in. long that are sometimes rolled at the tip. Flowering occurs June to November. The flowers occur in erect wands (panicles) 4-16 in. long and about 1/3 to 1 in. wide, each composed of 5 to 30 individual flowering spikes. The branch axes are triangular, with two rows of sessile, overlapping spikelets on the lower side. Spikelets are strongly flattened, keeled, and lanceolate, 8-15 mm long, with one floret and a pair of straight, unequal glumes. Spikelets detach from below the glumes. Glume and lemma keels are glabrous to sparsely covered with long, soft hairs and the ligule is hairy.
Catalog Number: US 81736
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): F. L. Scribner
Year Collected: 1895
Locality: Atlantic City., Atlantic, New Jersey, United States, North America
- Isotype: Merrill, G. M. 1902. U.S.D.A. Bur. Pl. Industr. Circ. 9: 9.
Catalog Number: US 865637A
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Verified from the card file of type specimens
Preparation: Pressed specimen
Collector(s): D. Richard
Locality: "America", North America
- Type fragment: Lamarck, J. B. A. 1791. Tabl. Encycl. 1: 180.
Catalog Number: US 878539
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Status verified by specimen annotations only
Preparation: Pressed specimen
Collector(s): J. H. F. Link
Locality: Unknown (N. Amer.)
- Type fragment: Sprengel, C. P. J., et al. 1820. Jahrb. Gewachsk. 1: 92.
Catalog Number: US 3376186
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Status verified by specimen annotations only
Preparation: Pressed specimen
Collector(s): G. Raddi
Locality: Minas Gerais, Brazil, South America
- Type fragment: Raddi, G. 1823. Agrostogr. Brasil. 21.
Smooth cordgrass forms dense, monospecific stands in salt and brackish
marshes with mid to high tide levels [6,27,30]. It dominates where
salinities range from 3 to 5 percent and the average water table is 4
inches (10.2 cm) above ground level. Plants may be inundated with salt
water for up to 20 hours per day. Unlike most other marsh plants, the
salt-tolerance of cordgrass is directly proportional to water depth .
Smooth cordgrass thrives in anoxic, low marsh habitats due to its
ability to oxygenate its roots and rhizosphere. Rhizosphere oxidation is
not evident in seedlings and small colonizing patches. Both of these
groups are stunted in anoxic low marsh substrates. This suggests that
success of smooth cordgrass in anoxic habitats is size dependent and may
be driven by group benefits of rhizosphere oxidation .
Key Plant Community Associations
Smooth cordgrass communities are true marsh communities, which have
surface water most of the time. In Louisiana, smooth cordgrass often
occurs in pure stands or with saltgrass (Distichlis spicata) and black
rush (Juncus roemerianus) as less abundant associates. Similar
communities have been described on Ocracoke Island, on islands off the
coasts of Mississippi and Louisiana, and for the Dismal Swamp. Smooth
cordgrass occurs in the understory of relatively open canopies of red
mangrove (Rhizophora mangle) swamps .
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES16 Oak - gum - cypress
FRES41 Wet grasslands
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K073 Northern cordgrass prairie
K078 Southern cordgrass prairie
Habitat in the United States
Smooth cordgrass grows on estuarine mudflats, in salt marshes, and in marsh sloughs (channels) and tolerates a wide range of salinity. On the west coast it has not been found to grow in freshwater marshes or on beaches that receive heavy wave action.
Depth range (m): 1.5 - 1.5
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Habitat & Distribution
Soil load-bearing properties -- It is not uncommon for soils (especially in dredge deposit sites) to be fluid to the point that they physically will not support the weight of plants. This is an indicator of soils with a very high water-to-mineral ratio.
High organic soils – Smooth cordgrass will not survive in soils with extremely high levels of organic matter. These soils are described as having very low bulk density and are problematic. When soil texture approaches the consistency of peat moss, there is potential for low plant survival.
Poor water circulation – Smooth cordgrass is critically sensitive to sulfide accumulations and has a relatively low tolerance to sulfide toxicity.
Shoreline configuration – Abrupt and steep cut-banks are indications of high wave energy and/or highly erodible soils. Special precautions may be required to keep transplants from dislodging prior to becoming established.
Herbivore grazing – Smooth cordgrass is a favorite of numerous grazing animals. In areas of heavy nutria population, caging plants may be required to protect newly planted material.
Smothering – Precautions should be taken when planting in areas of heavy floating debris. Both mechanical damage to the plants from surf-trash and smothering from water hyacinths are common.
Smooth cordgrass can be planted anytime past the last frost date if there is a need to plant earlier and available transplants are actively growing. In some areas this may be earlier than April 1.
In interior marshes with poor water circulation, avoid planting between mid-July and the end of August. Elevated water temperatures are generally detrimental to new transplants; therefore July and August plantings should be limited to lakes, bayous, and other areas of frequent tidal exchange.
Late fall plantings in October and November have been successfully made in the past, but should be limited to sites that are well protected and have minimal winter storm effect.
Adaptation: Smooth cordgrass is an inter-tidal brackish plant species. It is described as a facultative halophyte; that is, it will tolerate salt, but salt is not a requirement for its growth. Smooth cordgrass can be established in freshwater, however, numerous field trials have demonstrated that smooth cordgrass is difficult to establish and will not persist under freshwater field conditions. The ideal salinity range for establishing and growing smooth cordgrass is 8 to 33 parts per thousand or brackish to saline habitats. Smooth cordgrass can be established and will persists in areas of elevated salinity (such as salt-flats and tidal lagoons), however plants in high saline habitats tend to be stubby and less robust, generally resulting in thinner and more open vegetative stands.
Of primary importance in site selection is that the site be inter-tidal. Smooth cordgrass is critically sensitive to reduced soil sulfides, a condition common to anaerobic and brackish marsh soils. Smooth cordgrass should not be planted outside of the tidal zone. Smooth cordgrass will tolerate fluctuating water levels. Optimum water depths for establishing plants are 1” to 18”. Plantings in deeper water have been successful, however plants are slow to anchor and vegetative cover is sparse. Consequently, plants are more prone to washout, and minimal shoreline protection is achieved.
Smooth cordgrass is adapted to a wide range of soils from coarse sands to clays and mucks. Plant establishment and productivity appear to be superior on heavier mineral soils such as mucky clays, silty clays, silty clay loams, and fine sands. Soils with very high levels of organic matter pose structural problems and have proven to be problematic in establishing stands of smooth cordgrass.
Considerations: There are a number of other site-specific elements that should be considered when working with smooth cordgrass. These conditions represent extremes and should be thoroughly investigated prior to committing to a significant project if any of these conditions occur.
If any of these conditions are present, consult with a wetland specialist for additional information and/or possible alternatives.
Planting: Smooth cordgrass is a poor seed producer. Although plants appear to produce a significant number of seeds, most seeds are empty, damaged, or sterile. Consequently, seed fertility is low. For planting purposes, two forms of vegetative plant materials are recommended: containerized and bare-root plugs. Both plant forms have shown to be equally successful in establishing plant stands when planted properly and on applicable sites. There are no commercially available sources of seed, and seeding is not currently a recommended practice.
Smooth cordgrass can be produced in a number of container sizes, however trade-gallons are the most widely used and most popular size. Trade-gallon containers have a higher per unit cost compared to smaller containers or bare-root plugs, but provide the most reliable means of establishment. Trade-gallon plants have proven to be a highly successful transplant, especially along shorelines and other areas of high wave energy.
A trade-gallon will have 5 to 12 aerial stems that are 18” to 24” in height. Smooth cordgrass produces new tillers (stems) and spreads almost entirely from rhizomes. Consequently, a well-developed root mass is critical to the survival and productivity of transplants.
Bare-root plugs are the most economical of the commercially available plant sizes. Per unit production costs are low and transportation costs are very low compared to container plants. Bare-root plugs are generally limited to planting sites that have little or no energy exposure. Typical sites would include mudflats, sediment disposal areas, terraces, or other interior and protected sites. Bare-root plugs because of their limited surface area will not persist in high-energy environments. They tend to dislodge prior to establishing. Bare-root plugs have significantly less rootmass than container plants, will suffer a higher level of transplant shock, and are slower to spread than container plants. However, if handled properly and used on an applicable site, bare-root plugs can be highly successful transplants.
Bare-root plugs typically consist of 3 stems 12” to 18” in height, and stems should remain attached at the root. Plugs should have a rootmass of at least 2” in diameter at the root crown and 6” of root length.
A complete description (specification) for both trade-gallon container plants and bare-root plugs is available from the Natural Resources Conservation Service in Louisiana.
Planting Date: As a general rule, smooth cordgrass can be planted between April 1 to September 30. Some additional considerations include the following:
Planting Location: It is critically important to remember that smooth cordgrass is strictly an inter-tidal plant species and must be planted within the inter-tidal zone. Smooth cordgrass can be used for erosion control along shorelines, canal banks, levees, and other areas of soil-water interface. In addition, smooth cordgrass is an effective soil stabilizer used on interior tidal mudflats, dredge-fill sites, and other areas of loose and unconsolidated soils associated with marsh restoration.
Shoreline Plantings: Shoreline plantings are typically planted as a single row parallel to the shoreline. Transplants should be planted at the mid-point between the high and low tide elevations. Plant spacing within the row will vary according to the size of the transplant materials being used and the rate at which full coverage is desired. Trade-gallons generally are planted on 5’ to 8’ centers and plugs generally on 2’ to 3’ centers. Under applicable site conditions, smooth cordgrass will spread laterally filling spaces between plants and will grow up to its highest elevation and down to its lowest elevation. It is not uncommon for smooth cordgrass to produce 8’ to 10’ of lateral spread in one growing season.
Depending on site conditions and the planting objective, two rows of smooth cordgrass are occasionally planted. A two-row planting will provide quicker and denser short-term coverage than a single-row planting. If two rows are planted, rows should be parallel to each other and about 5’ apart using the same plant spacing within row as that of a single row. The first row should be placed slightly above the mean tide elevation and the second row 5’ below the first. Plants within the two rows should be staggered on center so that plants alternate between spaces.
Interior Plantings: In addition to planting shorelines, smooth cordgrass can also be used along terraces, levees, across mudflats and dredge-fill sites. The planting configuration should be designed to provide maximum reduction in fetch lengths. Rows can be placed across shallow water exchange points to create a passive hydrologic barrier that will slow tidal exchange and trap suspended sediments. Planting large areas generally will require a significantly large number of plants. Where applicable, plugs can be used and placed in a row-column configuration. The row and plant spacing can vary from a few feet to many, depending on the objective of the planting, the target rate for coverage, and available resources.
Planting Methods: When planting trade-gallons, transplants should be planted in a dug hole. Post-hole diggers, gas drills with modified bits, or any other methods of digging are satisfactory. The planting hole should be the same size or only slightly larger than the root-ball and deep enough so that the top of the root-ball is flush or slightly below ground. The top of the root-ball should not protrude above nor be more than 2” below normal ground. The planting hole should be tightly closed around the plant to prevent the plant from wobbling and plants should remain erect after planting.
Planting sites where high wave energy is a problem may require the addition of a plant anchor. A plant anchor consists of ¼” mild steel re-bar bent into a crosier hook (candy-cane shape) and pushed down into the soil so that hook lays across the root-ball, pinning it to the ground. Anchors are generally about 30” in overall length and will add to the cost of the planting. However, anchors are generally necessary at unusually problematic sites to prevent plants from washing out.
When planting bare-root plugs, holes need only be approximately 3” in diameter and deep enough to cover the roots. Any style of tool that will punch a hole this size such as a dibble bar will work. Cupping the roots of the plug in hand and pushing down into the mud carefully will also work in more fluid soils. There are no plant anchors for plugs, and in practice plugs should not be used at any site where wave energy is a factor.
Fertilization: There is no clear consensus on the effectiveness of fertilizer when used in saturated and/or anaerobic soils. However, the additional cost of fertilizer is a small investment given the overall cost involved in vegetative restoration. High nitrogen slow-release fertilizer tablets will add approximately .08 to .10 cents to the cost of an individual plant.
Slow-release fertilizer tablets are commercially available in a range of weights and analyses. Recommended tablet weight should be between 15 and 25 grams and have a nitrogen content of not less than 15% or more than 30%. When using tablets with trade-gallon plants, push the tablet into the top 3” of the root-ball immediately prior to or immediately after planting the transplant. The resulting hole should be pinched closed. When using tablets with bare-root plugs, drop the tablet in the planting hole prior to inserting the plug.
ascocarp of Buergenerula spartinae feeds on Spartina alterniflora
Foodplant / pathogen
ergot of Claviceps purpurea var. spartinae infects and damages live ovary of Spartina alterniflora
Foodplant / sap sucker
Prokelisia marginata sucks sap of Spartina alterniflora
Based on studies in:
USA: Massachusetts, Cape Ann (Marine)
This list may not be complete but is based on published studies.
- R. W. Dexter, The marine communities of a tidal inlet at Cape Ann, Massachusetts: a study in bio-ecology, Ecol. Monogr. 17:263-294, from p. 287 (1947).
The aquatic grass, which has the common name Smooth cordgrass, has a rhizomous rooting system, and manifests stem lengths of about 1.5 meters, with emergent leaves. This species has a very efficient photosynthetic capability at temperatures lower than some other genus members. Combined with its high salinity tolerance, this characteristic allows Smooth cordgrass to outcompete and hybridize with certain genus members, when it appears as an alien species. This phenomenon has occurred in the British Isles and along the west coast of California.
Fire Management Considerations
Marsh burns falls into three fairly distinct types, depending on the
condition of the marsh at the time of burning. This classification has
only been tested on the Gulf Coast, and should be experimentally tested
in other parts of the country before using .
(1) Cover burn - This is the most valuable and widely used
method of marsh burning. The marsh is burned when there are
from 3 to 5 inches (7.6 to 12.7 cm) of standing water present.
Dense vegetative cover will be removed allowing birds easier
access to food and facilitating muskrat trapping.
(2 & 3) Root burn and deep peat burn - Both burns occur without
standing water and are distinguished by the depth to
which the water table has dropped prior to the burn. These
burns may initially be destructive to wildlife, but wildlife
eventually benefit by habitat improvement.
Late summer and early fall burning controls greenhead flies by
destroying many of their eggs, but these fires may be detrimental to
other wildlife species .
Broad-scale Impacts of Plant Response to Fire
The Research Project Summary Vegetative response to fire exclusion and
prescribed fire rotation on 2 Maryland salt marshes provides information on
prescribed fire and postfire response of plant community species, including
smooth cordgrass, that was not available when this species review was written.
Plant Response to Fire
fires . Oil-covered plants burned following an oil-spill did not
survive, indicating that severe fires kill smooth cordgrass rhizomes
Rhizomatous herb, rhizome in soil
Fire is an important factor in the ecology of the Gulf Coast marshes.
Natural fires, caused by lighting and from spontaneous combustion in
dense stands, have resulted in a fire-dependent ecosystem. Growth
occurs year-round in southern marshes and the vegetation is so luxuriant
that an unburned marsh becomes a veritable tinder box within 3 to 4
Smooth cordgrass survives fire by tillering from rhizomes. Seeds may
colonize bare areas following fires which leave some adult plants to
More info for the term: marsh
Facultative Seral Species
Smooth cordgrass dominates the low marsh habitat in New England, and is
restricted to this habitat by the competitive dominance of marshhay
(Spartina patens) on the seaward border of the high marsh. In the
absence of marshhay, smooth cordgrass will grow vigorously in the high
Smooth cordgrass is a pioneer species bordering tidal inlets and lagoons
in the saline portions of Texas and Louisiana marshes . It also
invades brackish areas, ditches, and ponds with silt or clay bottoms,
and shallow water in saline areas. After organic matter builds up in
the ponds, brackish marsh dominants such as other cordgrasses (Spartina
spp.), saltgrass (Distichlis spp.), and rushes (Juncus spp.) replace
smooth cordgrass. Smooth cordgrass remains the major dominant in saline
areas, unless they are aggraded by inorganic sediments, which promotes
the establishment of communities of inland saltgrass or marshhay .
Smooth cordgrass reproduces both sexually and vegetatively. Sexual
reproduction contributes little to maintenance of established stands but
may be important in the establishment of large disturbance-generated
Sexual: Germination in New England marshes occurs from April until the
end of June . Germination response to salinity has an inverse
curvilinear relationship, with the maximum tolerance limit for
germination between 6 and 8 percent sodium chloride . Competition
from mature plants prevents seedling establishment. Maximum
establishment occurs on bare patches; seedling survival increases as
bare patch size increases. Tillers appear soon after germination and
spatial location of tillers may be important in determining seedling
Vegetative: Vegetative shoots grow in tussocks consisting of a parent
tiller plus daughter tillers developed from axillary buds at the base of
the parent shoot. Tussocks are connected by underground rhizomes .
Approximately 40 percent of rhizome growth occurs in the upper 2 inches
(5 cm) of soil from April to October. Over the whole year 74 percent of
the rhizome growth occurs in the upper 5.9 inches (15 cm) .
Growth Form (according to Raunkiær Life-form classification)
Immediate Effect of Fire
Life History and Behavior
In the North, smooth cordgrass plants have a short active period.
Shoots that develop during the summer die completely in the fall and are
often removed before mid-winter by ice and the tides. In the south, the
growing season is longer and fall senescence is slower. Many young
culms initiated in the fall live through the winter. Culms initiated
the previous spring do not complete senescence until the end of winter
. Flowering occurs from June until October [6,12,22]. Variety
pilosa flowers later than the typical form .
Biology and Spread
Reproduction of smooth cordgrass is primarily vegetative but sexual reproduction that results in seed production also plays a role. Rhizomes from a single plant spread outward in all directions, creating circular clones that eventually coalesce to form large extensive patches or meadows. Clumps of cordgrass can break off in winter storms and wash across the bay or into other bays and root in new areas. Viable pieces of cordgrass can also be spread by dredging equipment. Smooth cordgrass is wind-pollinated and is a mostly outcrossing species meaning that fertilization of the ovules requires pollen from other smooth cordgrass plants. The seeds are dispersed primarily by water and can be spread long distances by floating on racks of dead Spartina stems in the fall. The seeds remain viable for only one year and cannot tolerate desiccation. Plants die back starting in October and dead plant material is carried off by the tides to pile up in other locations, where it may smother native plants.
Molecular Biology and Genetics
Statistics of barcoding coverage: Spartina alterniflora
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Smooth cordgrass is a native species critical to Barrier Island and wetland restoration along the southeastern coastal states, while it is introduced into areas on the Pacific coast, where has become an aggressive invasive species. Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status, and wetland indicator values.
Gulf Coast marshes, because they provide soil stabilization and enhance
water quality, receive the highest priority for protection in
comprehensive oil spill response plans for coastal areas . Effects
of oil spills on salt marshes vary depending on oil type, plant
coverage, season, and marsh elevation . Flushing with seas water is
the most effective clean-up method for oil-contaminated salt marshes at
present. However, once oil penetrates the sediment, not even flushing
will remove it. Flushing is also ineffective at reducing damage to
cordgrass and enhancing long-term plant recovery. If natural tidal
flushing occurs, no other clean-up measures are recommended because
impacts on the community cause more harm than good. Overall, clean-up
responses have limited effectiveness; therefore, primary emphasis should
be placed on contingency planning and protection of salt marsh habitat
from oil spills .
Cultivars, improved and selected materials (and area of origin)
There are two known cultivars, ‘Vermilion’ and ‘Bayshore’. Vermilion was released in 1989 for use in the Gulf of Mexico northern basin, and Bayshore was released in 1992 for use on the Atlantic Coast. The Natural Resources Conservation Service Plant Materials Program released both.
Plant materials are generally obtained from two sources, a donor wetland site or commercial nurseries. The use of donor wetlands to obtain young plants will eventually affect the health and vigor of the donor stand regardless of the care taken in frequency, spacing, and location of plant removal. In addition, the removal of plant materials without the applicable permits may be in violation of standing state and federal regulations. Removing plant materials from donor stands is not recommended.
Nursery-grown stock is generally the most reliable and ecologically appropriate way to obtain plant materials. There are a number of commercial nurseries that produce and maintain smooth cordgrass transplants. Trade-gallon and vegetative plugs are the two most common sizes, however most nurseries will contract for other container sizes. Smooth cordgrass seed is currently not commercially available.
Vegetative specifications should be used to tailor plant material quality and quantity to a specific project. These specifications should include acceptable sources, cultivars, ecotypes, plant size, stem height, container specifications, and extent of root development. In addition, other requirements such as climatic hardening, salt hardening, procedures for transportation and handling are commonly included.
A list of commercial wetland plant nurseries and assistance in developing plant material specifications is available from the Natural Resources Conservation Service in Louisiana.
Smooth cordgrass has been introduced along the U.S. West Coast and is very invasive. Consult the links found at the bottom of the PLANTS Plant Profile for additional information regarding this species along the Pacific coast, particularly in California and Washington.
Relevance to Humans and Ecosystems
Other uses and values
Smooth cordgrass provides thatch for roofs .
Smooth cordgrass is an important component of Gulf Coast salt marshes
which stabilize shorelines against erosion and filter heavy metals and
toxic materials from the water column .
The presence of smooth cordgrass indicates sites with high salinity,
which can be managed for shrimp ponds .
Value for rehabilitation of disturbed sites
on dredge spoils from Connecticut to Virginia. Lower littoral zones
were seeded in locations where heavy wave action caused by storms did
not erode away the often top-heavy plants before their root systems
developed sufficiently. Smooth cordgrass seeds and seedlings were also
planted successfully on dredge spoils produced in the maintenance of
navigational channels within sounds and estuaries .
Smooth cordgrass provides cover for waterfowl, wading birds, shorebirds,
and muskrats; and habitat for commercially important fish and shellfish
Importance to Livestock and Wildlife
Smooth cordgrass has little value as livestock forage, although it is
sometimes eaten after rains wash away salts accumulated on the leaves.
Smooth cordgrass sites are often too wet for livestock grazing to be
A variety of wildlife species use smooth cordgrass. It is an important
food source for West Indian manatees (Trichechus manatus) and snow geese
(Chen caerulescens) [1,31]. It has provides limited food value for
muskrats (Ondatra spp.). Fiddler crabs (Uca pugnax) and ribbed mussels
(Geukensia demissa) form facultative mutualistic relationships with
smooth cordgrass. Fiddler crabs excavate burrows which increase soil
drainage, soil oxidation-reduction potential, and in situ decomposition
of belowground plant debris. Smooth cordgrass provides structural
support in the soft soil, which facilitates burrowing . Ribbed
mussels are found attached to stems and roots of smooth cordgrass. The
relationship leads to increased net primary production and stability of
the marsh .
SE US Coastal & Shoreline Restoration: Smooth cordgrass is a unique plant species that when established properly and under applicable conditions has proven to provide significant erosion protection to shorelines, canal banks, and other areas of coastal wetland loss.
Smooth cordgrass is used primarily for erosion control along shorelines, canal banks, levees, and other areas of soil-water interface. In addition, smooth cordgrass is an effective soil stabilizer used on interior tidal mudflats, dredge-fill sites, and other areas of loose and unconsolidated soils associated with marsh restoration. When established in conjunction with shorelines, smooth cordgrass provides an effective buffer that dissipates energy, reduces shoreline scouring, and traps suspended sediments and other solids. Dense stands of smooth cordgrass are efficient users of available nutrients, producing significant amounts of organic matter. The cumulative effects of organic matter production, sediment trapping, and erosion control not only provide shoreline protection but also accelerate sediment accumulation and near-shore building. Consequently, smooth cordgrass is a sustainable and renewable restoration resource, and when properly established and in the appropriate habitat, will persist and potentially remain effective indefinitely.
Ecological Threat in the United States
Where it is introduced, smooth cordgrass fills in mudflat habitats, transforming them into a dense meadow. As recently as 2003 smooth cordgrass had invaded between about 20,000 acres of tideflats in Willapa Bay, Washington and many acres in San Francisco Bay. This extensive invasive and replacement of native wetland vegetation has resulted in the loss of habitat for salmon and oysters and additional economic losses to those who rely on these species. The spread of smooth cordgrass in estuaries and channels also poses threats to navigation and flood control objectives.
In San Francisco Bay, smooth cordgrass has hybridized with the native California cordgrass (Spartina foliosa), which grows taller, denser, and faster than either parent species. Mapping efforts by the San Francisco Estuary Invasive Spartina Project found that the acreage invaded by hybrid cordgrass increased 52% between 2001 and 2004. One impact of hybrid cordgrass is its ability to trap sediment floating in the water. As the sediment builds up, each patch of smooth cordgrass becomes a small island. In San Francisco Bay, hybrid cordgrass has created islands up to 1 foot higher than the surrounding mudflats. Hybrid cordgrass can live both higher and lower in the intertidal zone than California cordgrass, which means that it also competes with pickleweed that grows higher in the marsh. Hybridization with California cordgrass in San Francisco Bay threatens the existence of the native California species, as it cannot compete with the reproduction and growth of the hybrid. This is a concern for the small invertebrates that live within the marsh, because their numbers are reduced within the dense roots of hybrid cordgrass, compared to the much sparser root system of California cordgrass. In both California and Washington, it also reduces habitat for shorebirds migrating on the Pacific flyway, which need to feed on open mudflats and will not enter thick vegetation. Endangered California clapper rails (Rallus longirostris obsoletus) using marshes invaded by hybrid cordgrass may be impacted as a result of habitat loss from cordgrass invasion.
Spartina alterniflora (smooth cordgrass or saltmarsh cordgrass) is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt marshes. It grows 1-1.5 m tall (3-5 feet,) and has smooth, hollow stems which bear leaves up to 20-60 cm (8 inches-2 feet) long and 1.5 cm (1/2 inch) wide at their base, which are sharply tapered and bend down at their tips. Like its relative Saltmeadow Cordgrass S. patens, it produces flowers and seeds on only one side of the stalk. The flowers are a yellowish-green, turning brown by the winter. It has rhizoidial roots, which, when broken off, can result in vegetative asexual growth. The roots are an important food resource for Snow Geese. It can grow in low marsh (frequently inundated by the tide) as well as high marsh (less frequently inundated), but it is usually restricted to low marsh because it is outcompeted by Saltmeadow Cordgrass in the high marsh. It grows in a wide range of salinities, from about 5 psu to marine (32 psu), and has been described as the "single most important marsh plant species in the estuary" of Chesapeake Bay. It is described as intolerant of shade.
S. alterniflora is noted for its capacity to act as an environmental engineer. It grows out into the water at the seaward edge of a salt marsh, and accumulates sediment and enables other habitat-engineering species, such as mussels, to settle. This accumulation of sediment and other substrate-building species gradually builds up the level of the land at the seaward edge, and other, higher-marsh species move onto the new land. As the marsh accretes, S. alterniflora moves still further out to form a new edge. S. alterniflora grows in tallest forms at the outermost edge of a given marsh, displaying shorter morphologies up onto the landward side of the Spartina belt.
Problems as an invasive species
Spartina alterniflora can become an invasive plant, either by itself or by hybridizing with native species and preventing propagation of the pure native strain. One example of an invasive Spartina alterniflora hybrid is that of S. anglica. S. anglica is a fertile polyploid derived from the hybrid S.alterniflora × townsendii (S. alterniflora × S. maritima), first found when American S. alterniflora was introduced to southern England in about 1870 and came into contact with the local native S. maritima. S. anglica has a variety of traits that allow it to outcompete native plants, including a high saline tolerance and the ability to perform photosynthesis at lower temperatures more productively than other similar plants. It can grow on a wider range of sediments than other species of Spartina, and can survive inundation in salt water for longer periods of time. S. anglica has since spread throughout northwest Europe, and (following introduction for erosion control) eastern North America.
In Willapa Bay of Washington state, Spartina alterniflora was probably an accidental introduction during oyster transplants during the nineteenth century. Presently, it covers 6,000-10,000 ha (15 to 25 thousand acres) of land, according to a 1999 estimate. In contrast, in the 1950s, under 160 ha (400 acres) of Spartina alterniflora were present. It is also making inroads into Puget Sound and Grays Harbor in Washington. The grass can hinder water circulation and drainage or block boating channels. Meadows of S. alterniflora can crowd out native species, reducing biodiversity and altering the environment; as a result of S. alterniflora's growth, invertebrates that live in mud flats disappear as their habitat is overgrown, and in turn, food sources shrink for birds who feed on those invertebrates.
In California, four species of exotic Spartina (S. alterniflora, S. densiflora, S. patens, and S. anglica) have been introduced to the San Francisco Bay region. Spartina alterniflora is well established in San Francisco Bay, and has had the greatest impact of all the cordgrasses in San Francisco Bay. It was introduced in 1973 by the Army Corps of Engineers in an attempt to reclaim marshland, and was spread and replanted around the bay in further restoration projects. It demonstrated an ability to outcompete the native S. foliosa, and to potentially eliminate it from San Francisco Bay.
Spartina alterniflora has also been found to hybridize with S. foliosa, producing offspring that may be an even greater threat than S. alterniflora by itself. The hybrid can physically modify the environment to the detriment of native species, and the hybrid populations have spread into creeks, bays, and more remote coastal locations. The hybrids produce enormous amounts of pollen, which swamp the stigmas of the native S. foliosa flowers to produce even larger numbers of hybrid offspring, leaving the native Spartina little chance to grow as a pure strain. The hybrids also produce much larger numbers of fertile seeds than the native Spartina, and are producing a hybrid population that is not only increasing in numbers, but increasing in its rate of population growth. The hybrids may also be able to fertilize themselves, which the native Spartina cannot do, and which increases the spread of the hybrid swarm even further.
Several means of control and eradication have been employed against Spartina alterniflora where it has become a pest. Hand pulling is effective, but only when done thoroughly and carefully, lest the plant's seeds spread to infest other areas. Glyphosate, an herbicide, is approved in Washington to kill it. In Willapa Bay, leafhopper bugs (Prokelisia marginata) have been employed to kill the plants, which threaten the oyster industry there. Surveys, by air, land, and sea are conducted in infested and threatened areas near San Francisco to determine Spartina's spread.
- http://www.fs.fed.us/database/feis/plants/graminoid/spaalt/all.html USDA Forest Service Fire Effects Information System (FEIS) for Spartina alterniflora
- Lippson, AJ & RL Lippson. 2006. Life in the Chesapeake Bay, 3rd ed., p.295. Johns Hopkins Press.
- http://plants.usda.gov/java/profile?symbol=spal USDA NRCS PLANTS profile for Spartina alterniflora
- 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. Accessed 7/24/12 at http://lamar.colostate.edu/~csbrown/BI528_2007/Genetics/Ayres%20et%20al%202004BioInv.pdf
- Callaway, J.C., and M. N. Josselyn. 1992. The introduction and spread of smooth cordgrass (Spartina alterniflora) in South San Francisco Bay. Estuaries 15: 218-226.
- Anttila, C. K., R. A. King, C. Ferris, D. R. Ayres, and D. R. Strong. 2000. Reciprocal hybrid formation of Spartina in San Francisco Bay. Molecular Ecology 9: 765-770. Accessed 7/24/12 at http://onlinelibrary.wiley.com/doi/10.1046/j.1365-294x.2000.00935.x/pdf
- Ayres D.R.; Garcia-Rossi D.; Davis H.G.; Strong D.R. 1999. Extent and degree of hybridization between exotic (Spartina alterniflora) and native (S. foliosa) cordgrass (Poaceae) in California, USA determined by random amplified polymorphic DNA (RAPDs). Molecular Ecology 8: 1179-1186. Accessed 7/24/12 at http://onlinelibrary.wiley.com/doi/10.1046/j.1365-294x.1999.00679.x/pdf
Names and Taxonomy
The currently accepted scientific name for smooth cordgrass is Spartina
alterniflora Loisel. (Gramineae). Recognized varieties and their
distribution are presented below [24,25,30]:
S. a. var. alterniflora: Maine, New Hampshire, Massachusetts, Rhode
S. a. var. glabra (Muhl.) Fern.: Florida
S. a. var. pilosa (Merr.) Fern.: Maine, New Hampshire, Massachusetts,
Rhode Island, Connecticut
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