Plant Assessment Form

More Nassella tenuissima resources

Nassella tenuissima

Synonyms: Stipa tenuissima

Common Names: Mexican feathergrass

Evaluated on: 05/10/2024

List committee review date: 04/04/2025

Re-evaluation date: 05/09/2025

Evaluator(s)

Nikki Valentine
California Invasive Plant Council
California Invasive Plant Council
510.843.3902 x306
nvalentine@cal-ipc.org

List committee members

Jutta Burger
Elizabeth Brusati
Chris McDonald
Justin Valliere
Ron Vanderhoff

General Comments

This species has received many reports of it volunteering prolifically and maintaining self-sustaining populations next to landscaped areas and trails since it was first listed as "Watch. Robust information about its ability to expand into undisturbed habitat is still lacking. Nasella tenuissima was listed as a "Watch" species from 2015 - 2025.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited

Alert Status? No Alert

Documentation? 3.5 out of 5

Score

Documentation

1.1

?Impact on abiotic ecosystem processes

C. Minor

Reviewed Scientific Publication

Impact?
Four-part score CUCD Total Score
C

1.2

?Impact on plant community

U. Unknown

Reviewed Scientific Publication

1.3

?Impact on higher trophic levels

C. Minor

Reviewed Scientific Publication

1.4

?Impact on genetic integrity

D. None

Other Published Material

2.1

?Role of anthropogenic and natural disturbance in establishment

B. Moderate

Reviewed Scientific Publication

Invasiveness?
Total Points
16 Total Score B

2.2

?Local rate of spread with no management

B. Increases less rapidly

Other Published Material

2.3

?Recent trend in total area infested within state

B. Increasing less rapidly

Other Published Material

2.4

?Innate reproductive potential
(see Worksheet A)

A. High

Reviewed Scientific Publication

2.5

?Potential for human-caused dispersal

A. High

Reviewed Scientific Publication

2.6

? Potential for natural long-distance dispersal

B. Occasional

Reviewed Scientific Publication

2.7

?Other regions invaded

B. Invades 1 or 2 ecological types

Other Published Material

3.1

?Ecological amplitude/Range
(see Worksheet C)

B. Moderate

Other Published Material

Distribution?
Total Score B

3.2

?Distribution/Peak frequency
(see Worksheet C)

B. Moderate

Observational

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? Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include: - fire occurrence, frequency, and intensity; - geomorphological changes such as erosion and sedimentation rates; - hydrological regimes, including soil water table; - nutrient and mineral dynamics, including salinity, alkalinity, and pH; - light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open). Select the one letter below that best describes this species' most severe impact on an abiotic ecosystem process: A. Severe, possibly irreversible, alteration or disruption of an ecosystem process. B. Moderate alteration of an ecosystem process. C. Minor alteration of an ecosystem process. D. Negligible perceived impact on an ecosystem process. U. Unknown.	C Reviewed Scientific Publication
Identify ecosystem processes impacted: Published observations of Nassella tenuissima to date report that it appears primarily as a waif in California wildlands (Calflora). Although Nassella tenuissima has very fine leaves that can increase fuel load and produces thousands of fine-awned seeds, it has not been observed forming dense infestations in California. Therefore, it is likely only minor wildfire hazard in those areas (Conolly and Taylor 2006; Calflora). This species' silica-rich, unpalatable leaves cycle slowly back to the soil, which results in alterations of the soil chemistry, which ultimately affects soil quality if established in larger numbers which does not occur in California wildlands (Moretto and Distel 2002). Sources of information: Calflora Observation Search. Available online: https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Conolly, Jenny and Taylor, Steve. 2006. Mexican feather grass (Nassella tenuissima) control - the ACT experience. Twentieth Australasian Weeds Conference. Available online: https://caws.org.nz/old-site/awc/2016/awc201612281.pdf Moretto, A.S.; Distel, R.A. Soil nitrogen availability under grass of different palatability in a temperate semi-arid rangeland of central Argentina. Austral Ecol. 2002, 27, 509–514. PlantRight. Stipa/Nassella tenuissima. Available online: https://plantright.org/invasive/stipanassella-tenuissima/. Accessed March 2024.
Question 1.2 Impact on plant community composition, structure, and interactions? Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include: - formation of stands dominated (>75% cover) by the species; - occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below; - significant reduction or extirpation of populations of one or more native species. Examples of impacts usually less than severe include: - reduction in propagule dispersal, seedling recruitment, or survivorship of native species; - creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer; - change in density or depth of a structural layer; - change in horizontal distribution patterns or fragmentation of a native community; - creation of a vector or intermediate host of pests or pathogens that infect native plant species. Select the one letter below that best describes this species' impact on community composition, structure and interactions: A. Severe alteration of plant community composition, structure, or interactions. B. Moderate alteration of plant community composition. C. Minor alteration of community composition. D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions. U. Unknown.	U Reviewed Scientific Publication
Identify type of impact or alteration: Nassella tenuissima primarily invades disturbed areas in California, making it is less likely to impact native plant communities (University and Jepson Herbaria 2011). Nassella tenuissima in Australia forms dense understory monocultures outcompeting and replacing native plants (Mapaura et al 2020; Government of South Australia; Humphries and Florentine 2021). However, there are no records of Nassella tenuissima forming dense infestations in California wildlands to date (Calflora). Sources of information: Calflora Observation Search. Available online: https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Government of South Australia. Mexican Feather Grass Weed Identification Notes. Available online: https://cdn.environment.sa.gov.au/landscape/docs/hf/mexican-feather-grass-identification-fact.pdf. Accessed March 2024. Humphries, Talia and Florentine, Singareyer. 2021. A Comparative Review of Six Invasive Nassella Species in Australia with Implications for Their Management. Plants, 10 (6). Available online: https://www.mdpi.com/2223-7747/10/6/1036#B54-plants-10-01036. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348. The University and Jepson Herbaria. 2011. "Stipa tenuissima Trin." UC Berkeley. Available online: https://ucjeps.berkeley.edu/cgi-bin/get_cpn?45645&expand=1. Accessed March 2025.
Question 1.3 Impact on higher trophic levels? Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species' net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types. Examples of severe impacts include: - extirpation or endangerment of an existing native species or population; - elimination or significant reduction in native species' nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors. Examples of impacts that are usually less than severe include: - minor reduction in nesting or foraging sites, cover, etc. for native animals; - minor reduction in habitat connectivity or migratory corridors; - interference with native pollinators; - injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species. Select the one letter below that best describes this species' impact on community composition and interactions: A. Severe alteration of higher trophic populations, communities, or interactions. B. Moderate alteration of higher trophic level populations, communities, or interactions. C. Minor alteration of higher trophic level populations, communities or interactions. D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions. E. Unknown.	C Reviewed Scientific Publication
Identify type of impact or alteration: Nassella tenuissima is unpalatable to most animals (Government of South Australia; Mapaura et al 2020). Additionally, Nassella spp. invasions in Australia (which form monocultures) are associated with reduced invertebrate diversity (Mapaura et al 2020). However, Nassella tenuissima primarily invades disturbed areas in California, making it is less likely to impact native communities in California (University and Jepson Herbaria 2011). Sources of information: Government of South Australia. Mexican Feather Grass Weed Identification Notes. Available online: https://cdn.environment.sa.gov.au/landscape/docs/hf/mexican-feather-grass-identification-fact.pdf. Accessed March 2024. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348. The University and Jepson Herbaria. 2011. "Stipa tenuissima Trin." UC Berkeley. Available online: https://ucjeps.berkeley.edu/cgi-bin/get_cpn?45645&expand=1. Accessed March 2025.
Question 1.4 Impact on genetic integrity? Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include: - production of fertile or sterile hybrids that can outcompete the native species; - production of sterile hybrids that lower the reproductive output of the native species. Select the one letter below that best describes this species' impact on genetic integrity: A. Severe (high proportion of individuals). B. Moderate (medium proportion of individuals). C. Minor (low proportion of individuals). D. No known hybridization. U. Unknown.	D Other Published Material
There is no evidence of this species hybridizing with native Nassella or Stipa species (Hickman 1993). Sources of information: Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA.
Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance in establishment? Assess this species' dependence on disturbance: both human and natural: for establishment in wildlands. Examples of anthropogenic disturbances include: - grazing, browsing, and rooting by domestic livestock and feral animals; - altered fire regimes, including fire suppression; - cultivation; - silvicultural practices; - altered hydrology due to dams, diversions, irrigation, etc.; - roads and trails; - construction; - nutrient loading from fertilizers, runoff, etc. Examples of natural disturbance include: - wildfire; - floods; - landslides; - windthrow; - native animal activities such as burrowing, grazing, or browsing. Select the first letter in the sequence below that describes the ability of this species to invade wildlands: A. Severe invasive potential: this species can establish independent of any known natural or anthropogenic disturbance. B. Moderate invasive potential: this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances. C. Low invasive potential: this species requires anthropogenic disturbance to establish. D. No perceptible invasive potential: this species does not establish in wildlands (though it may persist from former cultivation). U. Unknown.	B Other Published Material
Describe role of disturbance: Nassella tenuissima primarily spreads in disturbed areas through both natural and anthropogenic disturbance. The seeds have the potential to spread by wind, water, attachment to animal fur, attachment to clothing, and equipment. The species has a seed life of at least seven years (Moran et al 2018). Because Nassella tenuissima is not palatable, grazing further promotes its establishment. Introduced disturbance caused by management attempts such as burning or grubbing also further promote its establishment since Nassella teniussima can resprout if the roots are not fully removed or treated (Mapaura et al 2020; PIER 2024). N. tenuissima primarily invades disturbed grasslands (PIER 2004). Seedling establishment of N. tenuissima only occurs in microsites without shoot and root competition (Moretto and Distel 1998). For example, N. tenuissima in Australia invades undisturbed areas such as sparse understory and inter-tussock spaces (Conolly and Taylor 2006). Sources of information: Conolly, Jenny and Taylor, Steve. 2006. Mexican feather grass (Nassella tenuissima) control - the ACT experience. Twentieth Australasian Weeds Conference. Available online: https://caws.org.nz/old-site/awc/2016/awc201612281.pdf Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348. Moran, N.P.; Rowles, A.D.; Constantine, A.B. 10 years after Victoria’s major Mexican feather grass incursion: Assessing eradication methods and germination behaviour. In Weed Biosecurity—Protecting Our Future, Proceedings of the 21st Australasian Weeds Conference, Sydney, Australia, 9–13 September 2018; Johnson, S., Weston, L., Wu, H.W., Auld, B., Eds.; Council of Australasian Weed Societies Inc.: Sydney, Australia, 2018; pp. 109–114. Moretto, A.S.; Distel, R.A. Requirement of vegetation gaps for seedling establishment of two unpalatable grasses in a native grassland of central Argentina. Austral Ecol. 1998, 23, 419–423. PIER. Nassella tenuissima. Available online: http://www.hear.org/pier/species/nassella_tenuissima.htm (accessed March 2024).
Question 2.2 Local rate of spread with no management? Assess this species' rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented. Select the one letter below that best describes the rate of spread: A. Increases rapidly (doubling in <10 years) B. Increases, but less rapidly C. Stable D. Declining U. Unknown	B Other Published Material
Describe rate of spread: Nassella tenuissima is quick to invade disturbed or open areas and can quickly colonize an entire area in Australia (Russell and Rector 2023; Government of South Australia). Some isolated infestations in Australia did not become too large after several years (Conolly and Taylor 2006). Nassella tenuissima has been present in California for at least 20 years and has only been observed as waifs in disturbed areas (Calflora). Existing localized Nasella tenuissima infesations are not increasingly spreading. Sources of information: Calflora Observation Search. https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Conolly, Jenny and Taylor, Steve. 2006. Mexican feather grass (Nassella tenuissima) control - the ACT experience. Twentieth Australasian Weeds Conference. Available online: https://caws.org.nz/old-site/awc/2016/awc201612281.pdf Government of South Australia. Mexican Feather Grass Weed Identification Notes. Available online: https://cdn.environment.sa.gov.au/landscape/docs/hf/mexican-feather-grass-identification-fact.pdf. Accessed March 2024. Russell and Rector. 2023. Mexican feathergrass. Texas A&M. Availabe online: https://washington.agrilife.org/files/2023/04/Mexican-Feathergrass.pdf. Accessed March 2024.
Question 2.3 Recent trend in total area infested within state? Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them. Select the one letter below that best describes the current trend: A. Increasing rapidly (doubling in total range statewide in <10 years) B. Increasing, but less rapidly C. Stable D. Declining U. Unknown	B Other Published Material
Describe trend: The earliest reported observation in California is from 1998 (Calflora). Nassella tenuissima is capable of forming monocultures quickly in Australia in open or disturbed areas (Russell and Rector 2023). However, Nassella tenuissima has only been observed as waifs in disturbed areas in California with a stable trend in infested area in the past ten years (Calflora). Existing localized Nasella tenuissima infesations are not increasingly spreading. Sources of information: Calflora Observation Search. https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Russell and Rector. 2023. Mexican feathergrass. Texas A&M. Availabe online: https://washington.agrilife.org/files/2023/04/Mexican-Feathergrass.pdf. Accessed March 2024.
Question 2.4 Innate reproductive potential? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	A Reviewed Scientific Publication
Describe key reproductive characteristics: A single mature N. tenuissima plant can produce between 70,000–100,000 seeds annually, with up to 90% of the seeds germinating within their first two years, however small numbers can persist for over seven years (Humphries and Florentine 2021). Seeds are between 2 - 3mm long with a bristle-like appendage that is 4.5 - 9cm long extending from the end of the seed (Northern Territory Government of Australia 2017). N. tenuissima can cross-pollinate and self-pollinate (Humphries and Florentine 2021; Mapaura et al 2020). Flowering occurs August to February in Australia (Queensland Government 2016). In addition to the high seed production, vegetative regeneration has also been reported for this species with the presence of a bud bank. Nassella tenuissima produces 12 to 20 active buds per tiller or culm annually, allowing for vegetative regeneration after disturbance events (Russell 2007). Sources of information: Humphries, Talia and Florentine, Singareyer. 2021. A Comparative Review of Six Invasive Nassella Species in Australia with Implications for Their Management. Plants, 10 (6). Available online: https://www.mdpi.com/2223-7747/10/6/1036#B54-plants-10-01036. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. 2020. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 135, 336–348. Northern Territory Government of Australia: Department of Environment and Natural Resources. 2017. Mexican Feather Grass. Available online: https://depws.nt.gov.au/__data/assets/pdf_file/0019/404290/Mexican-feather-grass-ID-sheet-2017.pdf. Accessed March 2024. Queensland Government. 2016. Mexican Feather Grass. Available online: https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/biosecurity/plants/invasive/restricted/mexican-feather-grass. Accessed May 2024. Russell, M.L.; Rector, B.S. Mexican Feathergrass; Texas A&M AgriLife Extension: College Station, TX, USA, 2007; 4p.
Question 2.5 Potential for human-caused dispersal? Assess whether this species is currently spread: or has high potential to be spread: by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include: - commercial sales for use in agriculture, ornamental horticulture, or aquariums; - use as forage, erosion control, or revegetation; - presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.; - spread along transportation corridors such as highways, railroads, trails, or canals; - transport on boats or boat trailers. Select the one letter below that best describes human-caused dispersal and spread: A. High: there are numerous opportunities for dispersal to new areas. B. Moderate: human dispersal occurs, but not at a high level. C. Low: human dispersal is infrequent or inefficient. D. Does not occur. U. Unknown.	A Reviewed Scientific Publication
Identify dispersal mechanisms: Seeds are dispersed by many human-caused agents such as agricultural machinery, in mud or soil, clothing, trains, cars, silage, and hay in Australia (Mapaura 2020; NSW Weedwise 2021). Nassella tenuissima is also sold as a popular drought-tolerant ornamental in California. Many larger nurseries, like Home Deopt, stock and transport Nassella tenuissima. Nassella escapes residential plantings and spreads along urban roadways and sidewalks (Calflora). Sources of information: Calflora Observation Search. https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348. NSW Weedwise. Reviewed 2021. Mexican Feathergrass (Nassella tenuissima). Available online: https://weeds.dpi.nsw.gov.au/Weeds/MexicanFeatherGrass. Accessed May 2024.
Question 2.6 Potential for natural long-distance dispersal? We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms: - the species' fruit or seed is commonly consumed by birds or other animals that travel long distances; - the species' fruits or seeds are sticky or burred and cling to feathers or hair of animals; - the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water; - the species has light propagules that promote long-distance wind dispersal; - The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed). Select the one letter below that best describes natural long-distance dispersal and spread: A. Frequent long-distance dispersal by animals or abiotic mechanisms. B. Occasional long-distance dispersal by animals or abiotic mechanisms. C. Rare dispersal more than 1 km by animals or abiotic mechanisms. D. No dispersal of more than 1 km by animals or abiotic mechanisms. U. Unknown.	B Reviewed Scientific Publication
Identify dispersal mechanisms: N. tenuissima are usually only dispersed for short distances because their seeds remain attached to the plant (Mapaura 2020). N. tenuissima seeds in Australia are naturally dispersed by wind, water, contaminated soil, animal droppings, floodwaters, animal fur, and in mud or soil (Mapaura 2020; NSW Weedwise 2021). Although the panicles do not readily detach from N. tenuissima, their seeds are the smallest of all the Nassella species, which allows them to be effectively dispersed by wind (Marshal 2015). Sources of information: Marshal, A. Land of Sweeping Plains: Managing and Restoring the Native Grasslands of South-Eastern Australia; Williams, N., Marshall, A., Morgan, J., Eds.; CSIRO Publishing: Collingwood, Australia, 2015; 472p. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348. NSW Weedwise. Reviewed 2021. Mexican Feathergrass (Nassella tenuissima). Available online: https://weeds.dpi.nsw.gov.au/Weeds/MexicanFeatherGrass. Accessed May 2024.
Question 2.7 Other regions invaded? Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state. Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range. A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively). B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state. C. Invades elsewhere but only in ecological types that it has already invaded in the state. D. Not known as an escape anywhere else. U. Unknown.	B Other Published Material
Identify other regions: Nassella tenuissima is native to open, rocky scrublands and woods of the mountainous Trans-Pecos region of Texas west to southern New Mexico and south into central Mexico (Missouri Botanical Garden). This species is also native to Argentina and Chile (Missouri Botanical Garden). Nassella tenuissima has naturalized in New Zealand. In Australia, Nassella tenuissima invades grasslands, grassy woodlands, and montane forest understory. Nassella tenuissima is invasive in South Africa, where it occurs in montane grasslands (Mapaura et al 2020). There are observations of Nassella tenuissima reported in California largely along the coast from the Bay Area to San Diego (Calflora). In California this species has not yet invaded woodlands or forests. Sources of information: Calflora Observation Search. Available online: https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. Conolly, Jenny and Taylor, Steve. 2006. Mexican feather grass (Nassella tenuissima) control - the ACT experience. Twentieth Australasian Weeds Conference. Available online: https://caws.org.nz/old-site/awc/2016/awc201612281.pdf Missouri Botanical Garden. Nassella tenuissima. Available online: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=285344. Accessed May 2024. Mapaura, A.; Canavan, K.; Richardson, D.M.; Clark, V.R.; Steenhuisen, S.-L. The invasive grass genus Nassella in South Africa: A synthesis. S. Afr. J. Bot. 2020, 135, 336–348.
Section 3: Distribution
Question 3.1 Ecological amplitude/Range? Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades. A. Widespread: the species invades at least three major types or at least six minor types. B. Moderate: the species invades two major types or five minor types. C. Limited: the species invades only one major type and two to four minor types. D. Narrow: the species invades only one minor type. U. Unknown.	B Other Published Material
The earliest reported observation in California is from 1998 (Calflora). Nassella tenuissima has only been observed as a waif in California wildlands (Calflora). Observations of Nassella tenuissima reported in California occur largely along the coast from the Bay Area to San Diego (Calflora). These Calflora observations occur in riparian canyons, chaparral, coastal grasslands, and coastal scrub. N. tenuissima is also reported to occur in urban spaces, agricultural areas, forests, open grasslands, riparian zones, disturbed land, and shrublands. Sources of information: Calflora Observation Search. Available online: https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024.
Question 3.2 Distribution/Peak frequency? To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.	B Observational
Describe distribution: Occurs in less than 5% of any ecotype in California. This species is currently considered a waif (only an agricultural, garden, or urban weed) in California (The University and Jepson Herbaria). Sources of information: Calflora Observation Search. Available online: https://www.calflora.org/entry/observ.html?track=o#srch=t&taxon=Nassella+tenuissima&cols=0,3,36,13,38,11,41&chk=t&cch=t&cnabh=t&inat=r. Accessed March 2024. The University and Jepson Herbaria. 2011. "Stipa tenuissima Trin." UC Berkeley. Available online: https://ucjeps.berkeley.edu/cgi-bin/get_cpn?45645&expand=1. Accessed March 2025.

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less	Yes
Dense infestations produce >1,000 viable seed per square meter	Yes
Populations of this species produce seeds every year.	Yes
Seed production sustained over 3 or more months within a population annually	Unknown
Seeds remain viable in soil for three or more years	Yes
Viable seed produced with both self-pollination and cross-pollination	Yes
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes	No
Fragments easily and fragments can become established elsewhere	No
Resprouts readily when cut, grazed, or burned	Yes
Total points:	8
Total unknowns:	1
Total score:	A? Scoring Criteria for Worksheet A A. High reproductive potential (6 or more points). B. Moderate reproductive potential (4-5 points). C. Low reproductive potential (3 points or less and less than 3 Unknowns). U. Unknown (3 or fewer points and 3 or more Unknowns).

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? A means >50% of type occurrences are invaded; B means 20% to 50%; C means 5% to 20%; D means present but <5%; U means unknown (unable to estimate percentage of occurrences invaded)
Marine Systems	marine systems	U, Unknown
Freshwater and Estuarine	lakes, ponds, reservoirs	U, Unknown
Aquatic Systems	rivers, streams, canals	U, Unknown
Aquatic Systems	estuaries	U, Unknown
Dunes	coastal	U, Unknown
	desert	U, Unknown
	interior	U, Unknown
Scrub and Chaparral	coastal bluff scrub	U, Unknown
	coastal scrub	D, < 5%
	Sonoran desert scrub	U, Unknown
	Mojavean desert scrub (incl. Joshua tree woodland)	U, Unknown
	Great Basin scrub	U, Unknown
	chenopod scrub	U, Unknown
	montane dwarf scrub	U, Unknown
	Upper Sonoran subshrub scrub	U, Unknown
	chaparral	D, < 5%
Grasslands, Vernal Pools, Meadows, and other Herb Communities	coastal prairie	D, < 5%
	valley and foothill grassland	D, < 5%
	Great Basin grassland	U, Unknown
	vernal pool	U, Unknown
	meadow and seep	U, Unknown
	alkali playa	U, Unknown
	pebble plain	U, Unknown
Bog and Marsh	bog and fen	U, Unknown
Bog and Marsh	marsh and swamp	U, Unknown
Riparian and Bottomland habitat	riparian forest	U, Unknown
	riparian woodland	U, Unknown
	riparian scrub (incl.desert washes)	D, < 5%
Woodland	cismontane woodland	U, Unknown
	piñon and juniper woodland	U, Unknown
	Sonoran thorn woodland	U, Unknown
Forest	broadleaved upland forest	U, Unknown
	North Coast coniferous forest	U, Unknown
	closed cone coniferous forest	U, Unknown
	lower montane coniferous forest	U, Unknown
	upper montane coniferous forest	U, Unknown
	subalpine coniferous forest	U, Unknown
Alpine Habitats	alpine boulder and rock field
Alpine Habitats	alpine dwarf scrub	U, Unknown
	Amplitude (breadth):	B
	Distribution (highest score):	D

Infested Jepson Regions

Click here for a map of Jepson regions

Central West
Great Valley
Southwest