Plant Assessment Form

Medicago polymorpha

Common Names: California burclover; burr medic

Evaluated on: 3/19/05

List committee review date: 08/07/2005

Re-evaluation date:

Evaluator(s)

Bill Winans, Watershed Management Specialist
Dept. of Agriculture/Weights and Measures, County of San Diego
5555 Overland Ave. Suite 3101, San Diego, CA 92123
858 694-2777
bill.winans@sdcounty.ca.gov
Walter Graves, Environmental Management Specialist
County of San Diego
5555 Overland Ave. Suite 3101, San Diego, CA 92123
(858) 694-8893
walter.graves@sdcounty.ca.gov

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? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Observational
Impact?
Four-part score CCCD Total Score
C
1.2 ?Impact on plant community C. Minor Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels C. Minor Observational
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment C. Minor Observational
Invasiveness?
Total Points
9 Total Score C
2.2 ?Local rate of spread with no management C. Stable Reviewed Scientific Publication
2.3 ?Recent trend in total area infested within state C. Stable Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Other Published Material
2.5 ?Potential for human-caused dispersal C. Low Other Published Material
2.6 ? Potential for natural long-distance dispersal B. Occasional Other Published Material
2.7 ?Other regions invaded C. Already invaded Observational
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Reviewed Scientific Publication
Distribution?
Total Score A
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? C Observational
Identify ecosystem processes impacted:

Greater fire intensity may occur when nitrogen produced by this legume becomes available to other plants within the system. Higher nutrient levels in the soil allow the production of more biomass.


Sources of information:

observation


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

Grasslands are the areas where burclover most commonly grows. Native grasslands in California have been dramatically altered over the last 200 years by the introduction of European grasses. The growth of this legume may increase the thatch layer which, may effect the germination of other native and non-native plants within the system. Increased nutrient levels in the soil produced by the legume will favor plant species that can utiltize the enhansed resources. Higher nutrient levels in the soil alllow the production of more biomass.


Sources of information:

Observation


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

The higher nutrient levels in the legume will tend to stimulate herbivore populations. Herbivores often show preference for plant materials with greater nutrional value.


Sources of information:

observation


Question 1.4 Impact on genetic integrity? D Other Published Material

No known hybridization occurs. Not closely related to other native species.


Sources of information:

Hickman. 1993. The Jepson Manual.


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

Grazing livestock provide adequate disturbance for successful establishment of this plant. A prostrate growth habit increases it's survival even in the presence of moderate grazing pressure. The low growth habit also can work against the plant, as an overstory of taller grasses will cause the Burclover to fade out until the next disturbance event.


Sources of information:

Winan, observation


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

This plant has been in the state for two hundred years. It has likely spread to most of the locations where it can survive.


Sources of information:

Spira, T. P. and L. K. Wagner (1983) "Viability of Seeds up to 211 years old extracted from adobe brick building of California USA and Northern Mexico"


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

Grazed grasslands are the areas where this plant shows it's best growth. The plant does not appear to thrive well in areas outside of these parameters.


Sources of information:

observational


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

This is an annual plant, which produces seed within one year. Seeds remain viable for many years. The plant can recover from grazing as long as the grazing is not too severe.


Sources of information:

DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.


Question 2.5 Potential for human-caused dispersal? C Other Published Material
Identify dispersal mechanisms:

Human caused dispersal is not expected to be frequent. Seeds also disperse as commercial seed contaminants.


Sources of information:

DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.


Question 2.6 Potential for natural long-distance dispersal? B Other Published Material
Identify dispersal mechanisms:

The seed pods are covered with small hooks that effectively attach to animal hair. When livestock are moved the seed pods can be moved with them.


Sources of information:

DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.


Question 2.7 Other regions invaded? C Observational
Identify other regions:

This plant is wide spread throughout the world, but most prevalent in grasslands.


Sources of information:

observational


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? A Reviewed Scientific Publication

This plant is thought to have been introduced into Calif. in the 1700's when livestock was brought on sailing ships.Common in turf, roadsides, fields, grassland, pastures, agronomic crops, especially alfalfa, vegetable crops, orchards, vineyards, gardens, and other disturbed places.


Sources of information:

Spira, T. P. and L. K. Wagner (1983) "Viability of Seeds up to 211 years old extracted from adobe brick building of California USA and Northern Mexico"
DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.
Joanna Clines, US Forest Service, pers. obs.


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

Primarily found in grasslands. More frequent in grazed grasslands. Very wide spread throughout the states grasslands. High levels of infestation are not generally found unless the site is fertilized and moderately grazed.


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 No
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 Yes
Viable seed produced with both self-pollination and cross-pollination No
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: 4
Total unknowns: 0
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 prairieC, 5% - 20%
valley and foothill grasslandB, 20% - 50%
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 woodlandC, 5% - 20%
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forestD, < 5%
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): B

Infested Jepson Regions

Click here for a map of Jepson regions

  • CA Floristic Province
  • Cascade Range
  • Central West
  • Desert Province
  • Mojave Desert
  • Sonoran Desert
  • Great Valley
  • Modoc Plateau
  • Northwest
  • Sierra Nevada
  • Sierra Nevada East
  • Southwest