Plant Assessment Form

Euphorbia virgata

Synonyms: Euphorbia esula; Euphorbia discolor, Euphorbia virgata, Euphorbia gmelinii

Common Names: leafy spurge; faitours-grass; wolf's milk

Evaluated on: 1/18/05, info added 5/3/05

List committee review date: 12/10/2017

Re-evaluation date:

Evaluator(s)

Elizabeth Brusati, project manager
California Invasive Plant Council
1442A Walnut St. #462, Berkeley, CA 94709
510-843-3902
edbrusati@cal-ipc.org

List commitee members

Carla Bossard
Matt Brooks
Joe DiTomaso
Jake Sigg
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

Removed second scientific name, Euphorbia esula, and added it to the synonym line, 3/24/17. Ramona Robison

Table 2. Criteria, Section, and Overall Scores

Overall Score? High
Alert Status? No Alert
Documentation? 3.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Impact?
Four-part score UAAU Total Score
A
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels A. Severe Reviewed Scientific Publication
1.4 ?Impact on genetic integrity U. Unknown Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Reviewed Scientific Publication
Invasiveness?
Total Points
17 Total Score A
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 Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal A. Frequent Reviewed Scientific Publication
2.7 ?Other regions invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate
Distribution?
Total Score No score calculated
3.2 ?Distribution/Peak frequency
(see Worksheet C)
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? U Reviewed Scientific Publication
Identify ecosystem processes impacted:

In the Dakotas and other highly infested states, lands invaded by leafy spurge renders the land completely unusable from a soil and water profile standpoint. Causes lower water tables and erosion.


Sources of information:

Pirosko, Carri., California Dept. of Food and Agriculture. Personal communication. 3/11/05.enter text here


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

Allelopathic, dense roots outcompete other plants, reduces germination of native plants. Threatens the federally threatened species western prairie fringed orchid in North Dakota. Cover values of native species in Canada were negatively correlated with spurge (1). Germrination and greowth of other plants are inhibited by extracts from the roots of spurge (2). Growth of seedlings can be inhibited up to 60% when leafy spurge litter, roots, or leaves are incorporated into the soil (3).


Sources of information:

1. Belcher J.W., and S.D. Wilson S.D. 1989. Leafy Spurge and the Species Composition of a Mixed-grass Prarie. Journal of Range Management 42(2): 172-175
2. Best K.F., G. G. Bowes, A. G. Thomas, and M. G. Maw. 1980. The Biology of Canadian Weeds .39 Euphorbia esula L. Canadian Journal of Plant Science 60: 651-663
3. Steenhagen D.A., and R. L. Zimdahl R.L. 1979. Allelopathy of Leafy Spurge (Euphorbia esula). Weed Science 27(1): 1-3.
4. Lym, R.G. 2005. Leafy spurge (Euphorbia esula). In, Invasive plants of Range and Wildlands and Their Environmental, Economic, and Societal Impacts. Pp. 99-118.


Question 1.3 Impact on higher trophic levels? A Reviewed Scientific Publication
Identify type of impact or alteration:

Wildlife avoids eating it and it causes skin irritation. Reduces sparrow populations. Reduces habitat utilization by bison, deer, and elk. Caustic latex produced by plant causes blistering and loss of hair on horses' feet, and presumably has the same effect on wildlife (1).


Sources of information:

1. Best et al. 1980
Lym, R.G. 2005. Leafy spurge (Euphorbia esula). In, Invasive plants of Range and Wildlands and Their Environmental, Economic, and Societal Impacts. Pp. 99-118.


Question 1.4 Impact on genetic integrity? U Reviewed Scientific Publication

There are seven native Euphorbia species in California (1) and E. esula is known to hybridize (2). The leafy spurge present in the U.S. may actually be a hybrid between Old World spurges, resulting in genetic plasticity that allows it to adapt to a variety of conditions (3).


Sources of information:

1. Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA
2. Best et al. 1980
3. Goodwin, K., R. Sheley, R. Nowierski, and R. Lym. 2003. Leafy Spurge: Biology, Ecology and Management. Montana State University Extesion Publication . http://www.montana.edu/wwwpb/pubs/eb134.pdf


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

Mostly invades disturbed sites but is listed in native grasslands as well.


Sources of information:

1. Belcher and Wilson 1989
2. Best et al. 1980
3. Selleck G.W., R.T. Coupland, and C. Frankton. 1962. Leafy Spurge in Saskatchewan. Ecological Monographs 32(1):1-28.


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

Average annual spread within stands of brome in Canada was 50cm, while spread in ungrazed pasture was 64cm (1). In absence of competition, seedling roots can penetrate to three feet deep and spread 40 inches laterally in four months (2). Cattle will generally avoid leafy spurge and subsequently overgraze more desirable neighboring plants. This type of selection allows leafy spurge to rapidly establish large dense stands (3).


Sources of information:

1. Best et al. 1980
2. Goodwin et al. 2003
3. California Dept. of Food and Agriculture, Encycloweedia: Notes on Identification, Biology, and Management of Plants Defined as Noxious Weeds by California Law. Available: http://www.cdfa.ca.gov/phpps/ipc/weedinfo/euphorbia.htm. Accessed 5/3/05


Question 2.3 Recent trend in total area infested within state? B Observational
Describe trend:

no informationThe only large infestation (Siskiyou county, Klamath and Scott Rivers) is increasing. Small infestations (<100 plants each) in Modoc, Lassen, and Sierra counties are stable to decreasing.


Sources of information:

Pirosko, Carri., California Dept. of Food and Agriculture. Personal communication. 3/11/05.enter text here


Question 2.4 Innate reproductive potential? A Reviewed Scientific Publication
Describe key reproductive characteristics:

Perennial forb. Can reproduce in first year (1). Produces dense roots that spread rapidly. Most spread is vegetative (1). Usually requires cross-pollination, but can occasionally self-pollinate (2). New roots can branch from root nodes. Can resprout easily when roots are cut. Can produce 2500 seeds per m2 (1). After three years of burial, 64% of seeds were still viable at 20cm depth (1). High temperatures cause capsules to dehisce and throw seeds up to 5m from parent plant (1). Seeds can remain viable for 8 years (3). (Another study listed 5 yrs dormancy (4)). In Montana, seedlings rarely reproduce in first year (5). Roots can remain dormant until growing conditions are favorable (5), and can produce vegetative shoots for 5 years from a depth of 3 ft. after the major portion of the root system has been removed (4). In one study, patches increased by 30 - 387x within 5 years (4). Seedlings can reproduce vegetatively after 7-10 days emergence (4).


Sources of information:

1. Best et al. 1980
2. Selleck et al. 1962
3. Foley M.E. 2004. Leafy Spurge (Euphorbia esula) Seed Dormancy. Weed Science 52: 74-77
4. Selleck et al. 1962
5. Goodwin et al. 2003.


Question 2.5 Potential for human-caused dispersal? A Reviewed Scientific Publication
Identify dispersal mechanisms:

Domestic animals (1). Transport on farm or other machinery (2). Probably not intentional introduction. Most likely sources are driving tractor/ATV through patch and dispersing plant seeds or parts to another location; walking/hiking/rafting along river; new infestation brought into state through fire equipment, logging equipment or other gear. More likely to be spread by non-human dispersal (3).


Sources of information:

1. Selleck et al. 1962
2. Goodwin et al. 2003
3. Pirosko, Carri., California Dept. of Food and Agriculture. Personal communication. 3/11/05.


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

Spread by birds and animals. Seeds can float and germinate in water (1). Mostly dispersed by water movement, especially during floods (2).


Sources of information:

1. Selleck et al. 1962.
2. Pirosko, Carri., California Dept. of Food and Agriculture. Personal communication. 3/11/05.


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

Native to Europe. Present throughout US and into southern Canada (1, 2). Worldwide, ranges from xeric to subhumid habitats, and subtropical to subarctic (2). In Canada, occurs in abandoned pastures, native grasslands, and among trees and shrubs (3). Populations are small in California so there is a large potential for spread (4).


Sources of information:

1. USDA, NRCS. 2004. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
2. Selleck et al. 1962
3. Best et al. 1980
4. Pirosko, Carri. California Dept. of Food and Agriculture. Personal communication. 3/11/05.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B

Collected in coastal sage scrub, Los Angeles Co (1). In Canada, occurs in cropland, abandoned fields, grass pastures, native grasslands, and among trees and shrubs (2), and ranges from flat beds of glacial lakes to sand dunes to glacial moraines (3).In CA, occurs in Siskiyou, Modoc, Lassen, Sonoma, and Los Angeles Counties (4). Uncommon. Modoc Plateau (sw Modoc, se Lassen cos.). Previous infestations now considered eradicated in Cascade Ranges (ne Siskiyou Co.), eastern Klamath Ranges (cw Siskiyou Co.), southern North Coast Ranges (nw Sonoma Co.); to eastern U.S. To 1400 m (4600 ft) (1). In California, invades pasture, rangeland, borders of production ag fields, forested/woodland areas bordering range/pasture lands, sand bars in and along the Klamath River, and dry, upland forested areas such as juniper forest. May have been originally introduced into the state by miners as a medicinal plant (2).


Sources of information:

1. Unknown. 1997. Noteworthy Collections, California Madrono 44(2):203
2. Best et al. 1980
3. Selleck et al. 1962
4. USDA, NRCS. 2004.
1. California Dept. of Food and Agriculture, Encycloweedia: Notes on Identification, Biology, and Management of Plants Defined as Noxious Weeds by California Law. Available: http://www.cdfa.ca.gov/phpps/ipc/weedinfo/euphorbia.htm. Accessed 5/3/05
2. Pirosko, Carri., California Dept. of Food and Agriculture. Personal communications. 3/11/05 and 5/16/05.
3. Unknown. 1997. Noteworthy Collections, California. Madrono. 44(2):203


Question 3.2 Distribution/Peak frequency? Observational
Describe distribution:

Uncommon and only scattered populations in California so far.


Sources of information:

Pirosko, Carri., California Dept. of Food and Agriculture. Personal communication. 3/11/05.


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. Unknown
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 Yes
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 9
Total unknowns: 1
Total score: A?

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
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrubD, < 5%
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grasslandD, < 5%
Great Basin grasslandD, < 5%
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 woodlandD, < 5%
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): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions