Plant Assessment Form

Evaluated on: 12/30/2025

List committee review date: 06/02/2026

Re-evaluation date:

Evaluator(s)

Justin Valliere
University of California Davis
One Shields Ave, Davis, CA 95616
jmvalliere@ucdavis.edu

List committee members

Nikki Valentine
Jutta Burger
Umaina Khan

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate

Alert Status? No Alert

Documentation? 3 out of 5

Score

Documentation

1.1

?Impact on abiotic ecosystem processes

B. Moderate

Reviewed Scientific Publication

Impact?
Four-part score BBBC Total Score
B

1.2

?Impact on plant community

B. Moderate

Observational

1.3

?Impact on higher trophic levels

B. Moderate

Reviewed Scientific Publication

1.4

?Impact on genetic integrity

C. Minor/Low

Reviewed Scientific Publication

2.1

?Role of anthropogenic and natural disturbance in establishment

B. Moderate

Other Published Material

Invasiveness?
Total Points
16 Total Score B

2.2

?Local rate of spread with no management

A. Increases rapidly

Reviewed Scientific Publication

2.3

?Recent trend in total area infested within state

B. Increasing less rapidly

Observational

2.4

?Innate reproductive potential
(see Worksheet A)

A. High

Other Published Material

2.5

?Potential for human-caused dispersal

A. High

Other Published Material

2.6

? Potential for natural long-distance dispersal

D. None

Reviewed Scientific Publication

2.7

?Other regions invaded

A. Invades 3 or more ecological types

Other Published Material

3.1

?Ecological amplitude/Range
(see Worksheet C)

A. Widespread

Other Published Material

Distribution?
Total Score A

3.2

?Distribution/Peak frequency
(see Worksheet C)

A. High

Other Published Material

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.	B Reviewed Scientific Publication
Identify ecosystem processes impacted: Vicia villosa has been reported to contribute up to 80 kg N/ha per year in fixed N (Hargrove 1986), which represents a substantial amount of nitrogen inputs for natural ecosystems in California . Other sources state it can fix over 200 kg N/ha (Bryant 2026). Such levels of added N could be expected to promote invasive or weedy species over native plant species (Scherer-Lorenzen et al. 2007). Vicia villosa can also alter soil pH, redistribute extractable potassium, and lower CN ratios of the soil (Hargrove 1986). Plants can form spreading, tangled mats and climb over surrounding vegetation and other structures, thereby intercepting light and reducing light availability and quality to the soil surface and to plants growing beneath them (Teasdale and Daughtry 1993). Beneath living plants, light availability is often reduced to less than 1% of unobstructed sunlight (Teasdale and Daughtry 1993). Sources of information: Bryant, Peter J. “Winter Vetch.” Natural History of Orange County, California, n.d., https://nathistoc.bio.uci.edu/plants/Fabaceae/Vicia%20villosa.htm. Accessed 1 Jan. 2026. Hargrove, W. L. 1986. Winter Legumes as a Nitrogen Source for No-Till Grain Sorghum. Agronomy Journal 78:70-74. Scherer-Lorenzen, M., H. O. Venterink, and H. Buschmann. 2007. Nitrogen enrichment and plant invasions: the importance of nitrogen-fixing plants and anthropogenic eutrophication. Biological Invasions:163-180. Teasdale, J. R., and C. S. Daughtry. 1993. Weed suppression by live and desiccated hairy vetch (Vicia villosa). Weed science 41:207-212.
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.	B Observational
Identify type of impact or alteration: Quantitative data on the impacts of Vicia villosa on native plant communities are lacking. It is primarily a weed in agricultural systems and disturbed areas, but there is observational and anecdotal evidence that where established, it can dominate and outcompete native vegetation. As early as 1933, the species was noted as being a widespread escape capable of outcompeting both native and nonnative species (Wiggins 1933). The species is considered an escaped weedy species by UC IPM (UC ANR 2025a). It is noted (anecdotally) as harming native plants in California by UC Cooperative Extension expert Chris McDonald (UC ANR 2025b). There’s observational and other indirect evidence of negative impacts reported across multiple sites in California, including in agency reports and online resources. It is listed as one of the dominant nonnative species that have replaced natives in grasslands within Hellhole Canyon in San Diego County (ESA 2020), and the Restoration Committee of the San Diego Chapter of CNPS reports removing plants covering coastal sage scrub (Byrnes 2023). It is also categorized as invasive by Elings Park in Santa Barbara, and of the nearly 100 invasive species observed in the Park, it is one of the 32 species identified, mapped, and prioritized for possible removal (Elings Park, n.d.). Vicia villosa is also categorized as invasive in a rare plant survey report prepared for the City of Chico (WRA 2018). In upper Bidwell Park in Butte County, the species is ranked as a priority invasive species, but too widespread to control (Friends of Bidwell Park, n.d.). The species is on Marin Municipal Water District’s list of prohibited plants due to reported invasiveness (MMWD 2010). Lastly, there is evidence from a number of herbarium records which both implicitly and explicitly note impacts. The species has been reported as dominant and dense in a vernal pool complex near Sacramento (Collins 2023; CHSC 128170). Other herbarium notes describe it overtopping surrounding vegetation (Benefiel 2024; DAV 244497), and in some cases explicitly characterize it as “invasive” (Matheney 2022; SBBG 265276) or “an abundant weed” (Nelson 2015; JEPS 128420), including observations of site-level dominance (CNPS SN Foothill Team 2005; DAV 337602). Additional specimens document dominance and crowding of native wildflowers (Dean 2016; DAV 337601), and one record from Storke Ranch Open Space notes it as common, with control efforts underway (Hildner 2019; SBBG 161755). Sources of information: Byrnes, Robert. 2023. “Restoration Update: Hairy Vetch.” California Native Plant Society—San Diego Chapter. May 23, 2023. https://cnpssd.org/2023/05/23/2023-5-23-restoration-update-hairy-vetch/. Elings Park. (n.d.). Plant list from assessment. Retrieved January 1, 2026, from https://elingspark.org/park-ecology/ecological-assessment/plant-list/ ESA. 2020. Vegetation Management Plan for the Hellhole Canyon Preserve and Additions, County of San Diego Department of Parks and Recreation. Report prepared for the County of San Diego Department of Parks and Recreation. March 2020. https://www.sdparks.org/content/dam/sdparks/en/pdf/Resource-Management/management-documents/hellhole-canyon/vmp/Hellhole%20VMP%202020.pdf Friends of Bidwell Park. (n.d.). Potentially invasive plant species in Bidwell Park. Retrieved January 1, 2026, from https://friendsofbidwellpark.org/potentially-invasive-plant-species-in-bidwell-park/ Marin Municipal Water District. Invasive Plant List. May 2010, PDF. https://marinwater.org/wp-content/uploads/2022/02/Invasive_Plant_List.pdf University of California Agriculture and Natural Resources, UC Statewide Integrated Pest Management Program. 2025a. “Vetch (Vicia spp.).” UC IPM Weed Gallery. Accessed December 30, 2025. https://ipm.ucanr.edu/PMG/WEEDS/vetch.html. University of California Agriculture and Natural Resources, UC Integrated Pest Management Program. 2025b. “Questions and Answers from the UC IPM Urban and Community Webinar ‘Weeds, Wildlands and Wildfires’ (November 5, 2025).” PDF. November. https://ucanr.edu/sites/default/files/2025-11/Q%26A%20Weeds%20Wildlands%20and%20Wildfires_0.pdf. WRA, Inc. Rare Plant Survey Report: Stonegate Subdivision Project, City of Chico, Butte County, California. Prepared for the City of Chico, Feb. 2017, updated Mar. 2018. https://chicoca.gov/documents/Departments/Community-Development/Planning-Division/Current-Projects/appendixd-2_rareplantsurveyandmapping.pdf Herbarium record citations: Clifton Smith Herbarium, Santa Barbara Botanic Garden (SBBG). (2019). Vicia villosa subsp. villosa (Specimen SBBG161755; Occurrence ID 36a19ef1-f1f4-4a8a-9897-7fb459d0fa46), collected by K. Hildner (no. 83) on April 22, 2019, Goleta, Santa Barbara County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=2889721&clid=0 University of California, Davis Center for Plant Diversity (DAV). (2016). Vicia villosa Roth (Specimen DAV337601 [Accession DAV217619]; Occurrence ID a9c8cb1f-e410-4f45-aee9-0766b4726e96), collected by E. Dean (no. 8887) on May 12, 2016, Mix Canyon, Solano County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=1403264&clid=0 University of California, Davis Center for Plant Diversity (DAV). (2005). Vicia villosa Roth (Specimen DAV337602 [Accession DAV183399]; Occurrence ID 006875c6-9ff6-44a3-a704-137a445da948), collected by CNPS SN Foothill Team (SNFN-0025c) on March 25, 2005, Folsom State Recreation Area, El Dorado County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=1335824&clid=0 University and Jepson Herbaria, University of California, Berkeley (UC/JEPS). (2015). Vicia villosa Roth (Specimen JEPS128420; Occurrence ID UCJEPS:JEPS:JEPS128420), collected by J. Kierstead Nelson (no. 2015-002) on January 27, 2015, Redding, Shasta County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=3400115&clid=0 Clifton Smith Herbarium, Santa Barbara Botanic Garden (SBBG). (2022). Vicia villosa subsp. villosa (Specimen SBBG265276; Occurrence ID dc10db03-f300-4e8b-9ad6-475ce4ff1fc7), collected by M. Matheney (no. 5) on April 7, 2022, San Joaquin River Gorge, Fresno County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=5981606&clid=0 Ahart Herbarium, California State University, Chico (CHSC). “Vicia villosa subsp. villosa.” Specimen CHSC128170 (Occurrence ID 5913ee84-2dcc-4485-a3d8-d48860b1f69b), collected by Jordan Collins 1581 on April 14, 2023, Elk Grove, Sacramento County, California, USA. Consortium of California Herbaria (CCH2). Accessed December 31, 2025. https://cch2.org/portal/collections/individual/index.php?occid=6026499&clid=0 University of California, Davis Center for Plant Diversity (DAV). (2024). Vicia villosa Roth (Specimen DAV244497; Occurrence ID c1cd222d-b425-4819-8822-a926f444e89b), collected by S. Benefiel (no. 4) on April 27, 2024, Winters, Solano County, California, USA. Consortium of California Herbaria (CCH2). Retrieved December 31, 2025, from https://cch2.org/portal/collections/individual/index.php?occid=6010758&clid=0
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.	B Reviewed Scientific Publication
Identify type of impact or alteration: Vicia villosa seeds are toxic to cattle (Aguirre et al. 2021), pigs (Enneking 1995), and poultry (Harper and Arscott 1962). There is evidence that the species can disrupt plant-pollinator networks in California serpentine grasslands (Nelson 2024); as the ratio of invasive, non-serpentine flowers to native serpentine flowers increased, native plants received fewer pollinator visits, supported lower pollinator richness, produced fewer seeds, and played a diminished hub role in plant–pollinator networks. Sources of information: Aguirre, L. S., G. J. Cantón, E. L. Morrell, G. V. Sandoval, D. M. Medina, A. Avellaneda-Cáceres, and J. F. Micheloud. 2021. Retrospective analysis of hairy vetch (Vicia villosa roth) poisoning in Argentina (2004–2019). Toxicon 200:134-139. Enneking, D. 1995. The toxicity of Vicia species and their utilisation as grain legumes. Centre for Legumes in Mediterranean Agriculture (CLIMA) Occasional Publication 6. Harper, J., and G. Arscott. 1962. Toxicity of common and hairy vetch seed for poults and chicks. Poultry Science 41:1968-1974. Nelson, R. A. 2024. The Effects of Anthropogenic Global Changes on Prairie Plant-Pollinator Mutualisms. University of California, Davis.
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.	C Reviewed Scientific Publication
Donnelly and Clark (1962) assessed hybridization among four Vicia species, including V. villosa, finding that many interspecific pollinations produced no pods, or only immature or shriveled seeds. While there are native Vicia in California, these largely occur in different habitats and regions than V. villosa. A similar nonnative vetch, V. benghalensis, also occurs in similar habitats and behaves similarly, though no records of hybrids between the two species have been documented. Sources of information: Donnelly, E. D., & Clark, E. M. (1962). Hybridization in the Genus Vicia 1. Crop Science, 2(2), 141-145. Baldwin, B. G., & Goldman, D. H. (Eds.). (2012). The Jepson manual: vascular plants of California. Univ of California Press.
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.	A Reviewed Scientific Publication
Describe role of disturbance: Vicia villosa is commonly used as a cover crop and can become an agricultural weed, and also readily establishes in disturbed areas and along roadsides (UCANR 2025a; USDA NRCS 2012; USDA 2025). However, it also appears capable of invading native vegetation in the absence of disturbance (Lau and Suwa 2016; Catherine Koehler, personal communication). Sources of information: Lau JA, Suwa T (2016) The changing nature of plant–microbe interactions during a biological invasion. Biological Invasions 18:3527-3534 University of California Agriculture and Natural Resources, UC Statewide Integrated Pest Management Program. 2025a. “Vetch (Vicia spp.).” UC IPM Weed Gallery. Accessed December 30, 2025. https://ipm.ucanr.edu/PMG/WEEDS/vetch.html. USDA-Natural Resources Conservation Service, California Plant Materials Center. ‘Lana’ vetch (Vicia villosa subsp.varia).. Lockeford, CA 95237. Published [September, 2012], Revised [December, 2017]. USDA Forest Service. 2005. Hairy Vetch. https://www.invasive.org/weedcd/pdfs/wow/hairy-vetch.pdf
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	A Reviewed Scientific Publication
Describe rate of spread: Evidence from grasslands of northern California suggest Vicia villosa can spread rapidly. Between 2001 and 2003, the species was record in less than 5% of 132 surveyed grid points within grasslands at the UC McLaughlin Reserve (Davies et al. 2005). In 2010 when 118 of these grid point were resurveyed, the species was present in over 20% of plots (Lau and Suwa 2016). This represents over a four-fold increase in population size in less than ten years. Sources of information: Davies, K.F., Chesson, P., Harrison, S., Inouye, B.D., Melbourne, B.A. and Rice, K.J. (2005), SPATIAL HETEROGENEITY EXPLAINS THE SCALE DEPENDENCE OF THE NATIVE–EXOTIC DIVERSITY RELATIONSHIP. Ecology, 86: 1602-1610. https://doi.org/10.1890/04-1196 Lau, J.A., Suwa, T. The changing nature of plant–microbe interactions during a biological invasion. Biol Invasions 18, 3527–3534 (2016). https://doi.org/10.1007/s10530-016-1245-8
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 Observational
Describe trend: Based on documented observations, the species appears to be slowly spreading throughout the state in recent decades (Calflora 2026). In terms of geographic range, by 1985 the species was present in 46 counties, increasing to 51 in 1995. Currently, the species has been reported in 57 counties. Sources of information: “Calflora – Vicia villosa Taxon Report.” The Calflora Database, a non-profit organization. 2026. https://www.calflora.org/app/taxon?crn=8447 Accessed: January 01, 2026
Question 2.4 Innate reproductive potential? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	A Other Published Material
Describe key reproductive characteristics: Vicia villosa is an annual plant species which reaches reproductive maturity in a single year/growing season (Preston and Isely 2012). Based on existing literature regarding seed set, it seems likely that dense infestations could yield >1000 viable seeds per m2 (Renzi et al. 2025). The bloom period is at least three months, suggesting seed production could be sustained over this period (Calflora 2026). Accounts of seed viability are varied, but there are reports that seed can remain viable in the soil for over 5 years (UC IPM 2023). The species is primarily an out-crosser but is capable of self fertilization (Hamadi et al. 2012). Mowing and burning are suggested as effective control methods, so there is likely minimal resprouting (USDA 2005). There is no evidence that the species spreads through rhizomes or roots. Sources of information: Hamadi H, Aziza Z-K, Salah BY, Khouloud C, Safia E-B (2012) Analysis of floral Biology of Vicia villosa Roth.(Fabaceae). International Journal of Agricultural Sciences 2:iii+ 121-127 Renzi, J. P., M. Verdinelli, F. Santiago, F. Bilbao, and M. A. Cantamutto. 2025. Site-specific determinants of hairy vetch (Vicia villosa Roth) seed yield. Soil and Tillage Research 253:106682. Robert E. Preston & Duane Isely 2012, Vicia villosa, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=48101, accessed on January 01, 2026. “Calflora – Vicia villosa Taxon Report.” The Calflora Database, a non-profit organization. 2026. https://www.calflora.org/app/taxon?crn=8447 Accessed: January 01, 2026 University of California Statewide Integrated Pest Management Program (UC IPM). (2023). Vetch (Vicia spp.) (Weed Gallery). Retrieved January 1, 2026, from https://ipm.ucanr.edu/PMG/WEEDS/vetch.html USDA Forest Service. 2005. Hairy Vetch. https://www.invasive.org/weedcd/pdfs/wow/hairy-vetch.pdf
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 Other Published Material
Identify dispersal mechanisms: Vicia villosa is widely used as a cover crop in California, and it is known to spread readily along field edges, roads, and disturbed areas (UC IPM 2023). It is also spread as a a potential contaminant of crop seeds (Peralta De Andrés 2022). Sources of information: Peralta De Andrés J (2022) Vicia villosa (hairy vetch). CABI Compendium University of California Statewide Integrated Pest Management Program (UC IPM). (2023). Vetch (Vicia spp.) (Weed Gallery). Retrieved January 1, 2026, from https://ipm.ucanr.edu/PMG/WEEDS/vetch.html
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.	D Reviewed Scientific Publication
Identify dispersal mechanisms: Seeds of Vicia villosa are large and not readily dispersed other than when seed pods dry and dehisce (Cook 2002). Relatively large seed size likely limits long-distance dispersal (Yan et al. 2022). Seeds do not have any morphological characteristics to promote spread by wind or by attachment to animals. Seeds generally do not survive passage through the gut of animals (Armke and Scott 1999). Sources of information: Armke, F. W., & Scott, C. B. (1999). Using cattle to disperse seeds for winter forage plants. Texas Journal of Agriculture and Natural Resources, 12, 26-36 Cook, B.G., et al. (2022). Tropical Forages: an interactive selection tool Digital ISBN 978958694234-8. https://www.tropicalforages.info/text/intro/index.html. [Accessed January 2, 2026] Yang, C., Sun, R., Lu, X., Jin, T., Peng, X., Zhang, N., ... & Liu, W. (2022). Seed-germination ecology of Vicia villosa Roth, a cover crop in orchards. Agronomy, 12(10), 2488.
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.	A Other Published Material
Identify other regions: Vicia villosa has a global distribution due to its use in agriculture. It is considered invasive in Poland (Urbisz and Urbisz 2006), China (Xu et al. 2012), Canada (Peralta de Andrés 2022), Ukraine (Protopopova et al. 2006), and Chile (Bustamante et al. 2025). There are references to it being listed as invasive in other US States online, including Michigan (City of Ann Arbor 2021) and Oregon (Invasives.org), but no formal listings for Oregon could be verified. Sources of information: Bustamante RO, Alfaro A, Goncalves E, Duarte M (2025) Are range limits concordant with climatic niche requirements in alien plants? Leguminous invasive plants as case study, along a latitudinal gradient, central Chile. NeoBiota 98:27-42 Peralta De Andrés J (2022) Vicia villosa (hairy vetch). CABI Compendium Protopopova VV, Shevera MV, Mosyakin SL (2006) Deliberate and unintentional introduction of invasive weeds: A case study of the alien flora of Ukraine. Euphytica 148:17-33 Urbisz A, Urbisz A (2006) Invasive vascular plants species in the south-western part of the Silesian. Biodiv. Res. Conserv.:143-146 Xu H, Qiang S, Genovesi P, Ding H, Wu J, Meng L, Han Z, Miao J, Hu B, Guo J (2012) An inventory of invasive alien species in China. NeoBiota 15:1-26 City of Ann Arbor. 2021. City of Ann Arbor Invasive Species List. Revised November 2021. Maintained as provided under the Unified Development Code (UDC Article VIII: Definitions 5.37.2). https://www.a2gov.org/media/tvtcrt35/invasive-species-list-november-2021.pdf Invasive.org. n.d. Hairy vetch (Vicia villosa Roth). https://www.invasive.org/browse/subject/6614?tab=subject-info. Accessed 18 Jul 2026.
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.	A Other Published Material
There are herbarium records of Vicia villosa collected in California from the early 1900s (CCH2 2026). As early as 1933, the species was noted as being a widespread escape capable of outcompeting both native and nonnative species (Wiggins 1933). The species is widespread throughout California at lower elevations, generally <2,000 m, and is primarily found in grasslands, roadsides, and disturbed places (Preston and Isely 2012). It does occur in other lower elevation plant communities, such as coastal sage scrub, chaparral, riparian areas, and woodlands to a lesser extent (Calflora 2026; Valliere personal observation; Sandra DeSimone personal communication). Sources of information: “Calflora – Vicia villosa Taxon Report.” The Calflora Database, a non-profit organization. 2026. https://www.calflora.org/app/taxon?crn=8447 Accessed: January 01, 2026 CCH2 Portal. 2026. https://cch2.org/portal/index.php. Accessed on January 02. Robert E. Preston & Duane Isely 2012, Vicia villosa subsp. villosa, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=53359, accessed on January 02, 2026. Wiggins, I. L. 1933. NOTES ON THE INTRODUCED FLORA OF CALIFORNIA. Madroño 2:100-102.
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.	A Other Published Material
Describe distribution: Vicia villosa is widespread throughout California, with recorded observations in 57 counties (CCH2 2026; Calflora 2026). It is a widespread and common nonnative plant in the State’s grasslands and other open habitats at lower elevations (Calflora 2026). Sources of information: “Calflora – Vicia villosa Taxon Report.” The Calflora Database, a non-profit organization. 2026. https://www.calflora.org/app/taxon?crn=8447 Accessed: January 01, 2026 CCH2 Portal. 2026. https://cch2.org/portal/index.php. Accessed on January 02.

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	Yes
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	No
Total points:	8
Total unknowns:	0
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
Freshwater and Estuarine	lakes, ponds, reservoirs
Aquatic Systems	rivers, streams, canals
Aquatic Systems	estuaries
Dunes	coastal	D, < 5%
	desert
	interior
Scrub and Chaparral	coastal bluff scrub	D, < 5%
	coastal scrub	D, < 5%
	Sonoran desert scrub
	Mojavean desert scrub (incl. Joshua tree woodland)
	Great Basin scrub	D, < 5%
	chenopod scrub	U, Unknown
	montane dwarf scrub	U, Unknown
	Upper Sonoran subshrub scrub
	chaparral	D, < 5%
Grasslands, Vernal Pools, Meadows, and other Herb Communities	coastal prairie	A, > 50%
	valley and foothill grassland	A, > 50%
	Great Basin grassland	D, < 5%
	vernal pool	D, < 5%
	meadow and seep	C, 5% - 20%
	alkali playa	U, Unknown
	pebble plain
Bog and Marsh	bog and fen
Bog and Marsh	marsh and swamp
Riparian and Bottomland habitat	riparian forest	D, < 5%
	riparian woodland	D, < 5%
	riparian scrub (incl.desert washes)	D, < 5%
Woodland	cismontane woodland	D, < 5%
	piñon and juniper woodland	U, Unknown
	Sonoran thorn woodland
Forest	broadleaved upland forest	D, < 5%
	North Coast coniferous forest	D, < 5%
	closed cone coniferous forest	D, < 5%
	lower montane coniferous forest	D, < 5%
	upper montane coniferous forest	U, Unknown
	subalpine coniferous forest
Alpine Habitats	alpine boulder and rock field
Alpine Habitats	alpine dwarf scrub
	Amplitude (breadth):	A
	Distribution (highest score):	A

Infested Jepson Regions

Click here for a map of Jepson regions

CA Floristic Province
Cascade Range
Central West
Great Valley
Northwest
Sierra Nevada
Great Basin Province
Modoc Plateau
Sierra Nevada East

California Invasive Plant Council

Protecting California’s environment and economy from invasive plants

Plant Assessment Form

Evaluator(s)

List committee members

General Comments

Table 2. Criteria, Section, and Overall Scores

Table 3. Documentation

Worksheet A - Innate reproductive potential

Related traits:

Worksheet C - California Ecological Types

Infested Jepson Regions