Plant Assessment Form

Euphorbia oblongata

Common Names: eggleaf spurge; oblong spurge

Evaluated on: 1/26/05

List committee review date: 08/07/2005

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
Joseph DiTomaso
University of California-Davis
Dept. Plant Sci., Mail Stop 4, Davis, CA 95616
530-754-8715
jmditomaso@ucdavis.edu

List commitee members

Joe DiTomaso
Joanna Clines
Cynthia Roye
Doug Johnson

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Impact?
Four-part score UCUU Total Score
C
1.2 ?Impact on plant community C. Minor Other Published Material
1.3 ?Impact on higher trophic levels U. Unknown
1.4 ?Impact on genetic integrity U. Unknown
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
10 Total Score C
2.2 ?Local rate of spread with no management B. Increases less rapidly Observational
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)
B. Moderate Other Published Material
2.5 ?Potential for human-caused dispersal D. Does not occur Observational
2.6 ? Potential for natural long-distance dispersal C. Rare Observational
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low 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:

No information available. Considered a noxious weed, but are much less problematic relative to leafy spurge.


Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
C Other Published Material
Identify type of impact or alteration:

Similar to leafy spurge (1). Allelopathic, dense roots outcompete other plants, reduces germination of native plants (based on leafy spurge references). Does not currently form the dense stands typical of leafy spurge.


Sources of information:

1. Anonymous. Eggleaf spurge. Written findings of the Washington State Noxious Weed Control Board. www.nwcb.wa.gov/weed_info/eggleafspurge.html


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

The milky sap of this species may have irritant properties, but toxicity problems have not been reported.


Sources of information:

Question 1.4 Impact on genetic integrity? U

There are seven native Euphorbia in California, so potential for hybridization is there. There is no evidence for hybridization though.


Sources of information:

Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA enter text here


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

Euphorbia spp. often found in waste places, roadsides, fields, pastures, but can move into relatively undisturbed sites.


Sources of information:

California Department of Food and Agriculture. Encycloweedia. Available: http://www.cdfa.ca.gov/phpps/ipc/encycloweedia/encycloweedia_hp.htm


Question 2.2 Local rate of spread with no management? B Observational
Describe rate of spread:

Appears to be spreading locally, but not at rates observed for leafy spurge.


Sources of information:

DiTomaso, observational.


Question 2.3 Recent trend in total area infested within state? B Other Published Material
Describe trend:

Expanding range. Rated a B weed in California.


Sources of information:

Encycloweedia


Question 2.4 Innate reproductive potential? B Other Published Material
Describe key reproductive characteristics:

Perennial. Monoecious. Spreads by seed or division. Crown buds develop at the bases of stems and can produce new shoots or roots. The biology of these species is poorly understood.


Sources of information:

Washington State Noxious Weed Control Board


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

Not typically sold in the nursery industry so opportunities for human dispersal are rare.


Sources of information:

DiTomaso, observational.


Question 2.6 Potential for natural long-distance dispersal? C Observational
Identify dispersal mechanisms:

Seed primarily fall to ground below parent plant. No mechanism of long distance dispersal. Can occur close to water and this could move seed long distances on occasion.


Sources of information:

DiTomaso, observational.


Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

Native to southwestern Europe. Listed as a Class A noxious weed in Washington (1). Also in Oregon.


Sources of information:

1. Washington State Noxious Weed Control Board.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? A Other Published Material

In native range, inhabits damp meadows, shady woodlands, waste areas, and dry hillsides (1). Uncommon but expanding range in California. Present in Central Valley, San Francisco Bay Area, southern Cascade Range, southern North Coast and North Coast Ranges, South Coast Ranges, northern and central Sierra foothills to 200m (Encycloweedia). Mainly observed as an urban weed, but can be found in riparian areas and in woodlands.


Sources of information:

1. Washington State Noxious Weed Control Board.
DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.


Question 3.2 Distribution/Peak frequency? D Observational
Describe distribution:

Uncommon in California, but expanding range. Central Valley, San Francisco Bay region, southern Cascade Range, southern North Coast and North Coast Ranges, South Coast Ranges, northern and central Sierra Nevada foothills, to 200 m.


Sources of information:

DiTomaso, observational.


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 No
Seeds remain viable in soil for three or more years Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 5
Total unknowns: 2
Total score: B?

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 scrub
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 grassland
Great Basin grassland
vernal pool
meadow and seepD, < 5%
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodlandD, < 5%
riparian scrub (incl.desert washes)
Woodlandcismontane woodlandD, < 5%
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forestD, < 5%
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

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada