Plant Assessment Form

Spartina patens

Synonyms: Spartina versicolor (Spain)

Common Names: Salt marsh hay

Evaluated on: 9/9/04

List committee review date: 11/02/2005

Re-evaluation date:


Dr. Debra Ayres
UC Davis
Evolution and Ecology, 1 Shields Ave., UC Davis, 95616
530 752 6852

List commitee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes D Observational
Four-part score DAUD Total Score
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels U. Unknown
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Reviewed Scientific Publication
Total Points
7 Total Score C
2.2 ?Local rate of spread with no management B. Increases less rapidly Reviewed Scientific Publication
2.3 ?Recent trend in total area infested within state C. Stable Reviewed Scientific Publication
2.4 ?Innate reproductive potential
(see Worksheet A)
U. Unknown
2.5 ?Potential for human-caused dispersal U. Unknown
2.6 ? Potential for natural long-distance dispersal C. Rare Reviewed Scientific Publication
2.7 ?Other regions invaded C. Already invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
D. Narrow Reviewed Scientific Publication
Total Score D
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Reviewed Scientific Publication

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? D Observational
Identify ecosystem processes impacted:

None In its native range, ecosystem modifications have not been noted.

Sources of information:

Work by Mark Bertness in and referenced in:
Bertness MD, Ellison AM. 1987. Determinants of pattern in a New England salt marsh plant community. Ecological Monographs 57: 129-147.

Question 1.2 Impact on plant community composition,
structure, and interactions?
A Reviewed Scientific Publication
Identify type of impact or alteration:

S. patens overgrows the mid-marsh (Salicornia virginica in CA) communities where it occurs. The primary effect of this invasion is the threat it poses to one of the few remaining populations of Cordylanthus mollis mollis, a Federally listed species.

Sources of information:

In CA: Ayres DR, et al. 2004. Spread of exotic cordgrasses and hybrids (Spartina sp.) in the tidal marshes of San Francisco Bay, California, USA. Biological Invasions 6: 221-231.
In Oregon: Frenkel RE and Boss TR. 1988. Introduction, establishment and spread of Spartina patens on Cox Island, Suislaw estuary, Oregon. Wetlands 8: 33-49

Question 1.3 Impact on higher trophic levels? U
Identify type of impact or alteration:

None known in CA or reported its native range Note from reviewing committee: possible effects on endangered salt marsh harvest mouse?

Sources of information:

Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

No known hybridization with other Spartina sp. and phylogenetically distant from S. foliosa

Sources of information:

Baumel A, et al. 2002. Molecular phylogeny of the hybridizing species from the genus Spartina. Molecular Phylogenetics and Evolution 22: 303-314.

Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
B Reviewed Scientific Publication
Describe role of disturbance:

Wrack-generated bare patches are covered by rhizome growth on the Eastern US coast. Open patches are also where seed recruitment may occur. We expect the species behaves similarly here with a dependence on naturally occuring disturbance patches.

Sources of information:

Bertness and Ellison. 1987

Question 2.2 Local rate of spread with no management? B Reviewed Scientific Publication
Describe rate of spread:

In OR, exponential. In CA, 2 plants in 1970 have expanded to 42 plants.

Sources of information:

Frenkel and Boss; Ayres et al 2004

Question 2.3 Recent trend in total area infested within state? C Reviewed Scientific Publication
Describe trend:

One site in Southhampton Marsh near Benecia in 1970, still just 1 site. Repeat monitoring will allow an estimate of growth rate of this single population.

Sources of information:

Ayres et al;

Question 2.4 Innate reproductive potential? U
Describe key reproductive characteristics:

Too many unknowns to score.

Sources of information:

Question 2.5 Potential for human-caused dispersal? U
Identify dispersal mechanisms:

no information

Sources of information:

Question 2.6 Potential for natural long-distance dispersal? C Reviewed Scientific Publication
Identify dispersal mechanisms:

Seedlings occur close to established plants on the Eastern US coast, but it is not known how far seed will travel.

Sources of information:

Rand TA. 2000. Seed dispersal, habitat suitability, and the distribution of halophytes across a salt marsh tidal gradient. Journal of Ecology 88: 608-621

Question 2.7 Other regions invaded? C Reviewed Scientific Publication
Identify other regions:

Cox Island, OR; Hood Canal, WA; Tasmania, Australia; China

Sources of information:

Grossinger, R., J. Anderson, A. Cohen, and J. Collins. 1998. Introduced Tidal Marsh Plants in the San Francisco Estuary. San Francisco Estuary Institute. Richmond, CA. Accessed on-line:

Section 3: Distribution
Question 3.1 Ecological amplitude/Range? D Reviewed Scientific Publication

Occurs in the Salicornia zone in San Francisco Bay (Ayres et al 2004); above the Spartina alterniflora zone on the East coast (Bertness and Ellison, 1987), from which we infer that it is not as tolerant to innundation as taller cordgrasses, but can form dense turfs that exclude S. alterniflora at higher tidal elevation. Waa first noticed in 1970.

Sources of information:

see above

Question 3.2 Distribution/Peak frequency? D Reviewed Scientific Publication
Describe distribution:

Single population in Southhampton marsh, Benecia (although P. Baye has reported an additional occurence in the North Bay).

Sources of information:

Ayres et al, 2004

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Unknown
Dense infestations produce >1,000 viable seed per square meter Unknown
Populations of this species produce seeds every year. Unknown
Seed production sustained over 3 or more months within a population annually Unknown
Seeds remain viable in soil for three or more years Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere Unknown
Resprouts readily when cut, grazed, or burned Yes
Total points: 2
Total unknowns: 7
Total score: U?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuariesD, < 5%
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): D
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West