Froelichia gracilis (Hook.) Moq.; Slender snakecotton

California Pest Rating for
Froelichia gracilis (Hook.) Moq.; Slender snakecotton
Amaranthaceae: Caryophyllales
Pest Rating: D  |  Proposed Seed Rating: None


Initiating Event:

The species was given a temporary Q rating in 2014.

History & Status:

Slender snakecotton is an herbaceous, short-lived perennial (often an annual in weedy situations) that can grow 20-70 cm in length. The plant branches from the base, creeping along the ground and then becoming erect. The whole plant is covered in white, silky hairs. The leaves occur mostly on the lowers parts of stems and are narrowly lanceolate, narrower than in closely related taxa. The largest leaves measure 8 cm (3 in.) long and 1 cm wide. The apetalous flowers of Froelichia gracilis are arranged in a 3-rowed spiral on 1-3 cm long spikes and appear in summer to early fall. The seeds of this plant are small, measuring 1.2-1.4 mm. Although widely distributed and native to the southern United States, slender snakecotton seems not to be native to California. It is a weedy species of roadsides, railroads, farms and pastures, riverbanks, vacant lots, overgrazed rangelands, and sandy soils. It tolerates cold winters, but can also occur in moist subtropical areas.

Official Control: Slender snakecotton has been a “Q” listed weed in California since late 2014.

California DistributionSlender snakecotton is known from 3 interceptions in California (two from Los Angeles and one from Shasta County).

California Interceptions: Vouchered specimens are known from Los Angeles and Shasta Counties.

United States:  Slender snakecotton is widespread in the Southern United States. It is generally viewed as adventive in the northern and northeastern U.S. It is listed as a noxious weed in Connecticut.

International: Slender snakecotton is reported as naturalized and as an environmental and agricultural weed in Queensland, Australia.

The risk Slender snakecotton would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: It is an invasive species of roadsides, railroads, farms, riverbanks, vacant lots, overgrazed rangelands, and sandy areas. It is been detected in 2 counties with radically different climates, but has not spread widely. Although it may spread in agricultural situations with adequate water, its rarity in the state, despite being native to nearby states, indicates that it is unlikely to spread quickly. Therefore. It scores as Low (1) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score:

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.

-Medium (2) may be able to establish in a larger but limited part of California.

-High (3) likely to establish a widespread distribution in California.

2) Host Range: Risk is High (3) as weeds do not require any one host, but grow wherever ecological conditions are favorable.

Evaluate the host range of the pest. Score:

-Low (1) has a very limited host range.

-Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Slender snakecotton produces numerous seeds that can spreads via agricultural activity. Slender snakecotton receives a Medium (2) in this category.

Evaluate the natural and artificial dispersal potential of the pest. Score:

-Low (1) does not have high reproductive or dispersal potential.

Medium (2) has either high reproductive or dispersal potential.

-High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Slender snakecotton is a weed in some agricultural situations. There is little report of significant effects however. Slender snakecotton receives a Low (1) in this category.

Evaluate the economic impact of the pest to California using the criteria below. Score:

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

The organism can interfere with the delivery or supply of water for agricultural uses.

Low (1) causes 0 or 1 of these impacts.

-Medium (2) causes 2 of these impacts.

-High (3) causes 3 or more of these impacts.

5) Environmental Impact: The plant has not yet spread widely in California. If it does spread, Slender snakecotton might trigger new treatments by land managers. As it invades open areas, it may outcompete native plants that also colonize open, sandy soils. Slender snakecotton receives a Low (1) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest could significantly impact cultural practices, home/urban gardening or ornamental plantings.

          Score the pest for Environmental Impact.

-Low (1) causes none of the above to occur.

-Medium (2) causes one of the above to occur.

-High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Slender snakecotton: Low (8)

Add up the total score and include it here.

-Low = 5-8 points

-Medium = 9-12 points

-High = 13-15 points

6)  Post Entry Distribution and Survey Information: Slender
snakecotton has been found in in 2 counties in California. Its range at this time is limited. It receives a Medium (-2) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

-Not established (0) Pest never detected in California, or known only from incursions.

-Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

-High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Low (6)


The rarity of this plant in California despite being first detected in Los Angeles in 1955 and its widespread range in the rest of North America render it unlikely that this plant will invade many new areas and increase its density and acreage.

Conclusion and Rating Justification:

Slender snakecotton deserves an D rating at this time, because of its limited range in California, despite being native to nearby states.


Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Consortium of California Herbaria:

Csurhes S.  & Y. Zhou . 2008. Weed Risk Assessment of Cotton-tails, Froelichia floridana and F. gracilis. Biosecurity Queensland Department of Primary Industries and Fisheries, Brisbane, Australia.

Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  16+ vols.  New York and Oxford.

Reed, C. F. 1962. New records for Froelichia in eastern United States. Castanea 27: 59-61.

USDA Plant Profile: Froelichia gracilis. Accessed May 16, 2015:

Washington State Weed Control Board: Slender snakecotton. Accessed September 16, 2014:

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312;[@]

Comment Period: CLOSED

The 45-day comment period opened on Monday , October 19, 2015 and closed on December 3, 2015.

Pest Rating: D  |  Proposed Seed Rating: None

Posted by ls