Plant Assessment Form

Egeria densa

Common Names: Brazilian egeria; egeria

Evaluated on: 5/22/03

List committee review date: 06/06/2003

Re-evaluation date:

Evaluator(s)

Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616
530-754-8715
DiTomaso@vegmail.ucdavis.edu

List commitee members

Joe DiTomaso
Peter Warner
Alison Stanton
Carla Bossard
Cynthia Roye
Jake Sigg
Doug Johnson
Brianna Richardson

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? High
Alert Status? No Alert
Documentation? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes A Reviewed Scientific Publication
Impact?
Four-part score AAAD Total Score
A
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels A. Severe Other Published Material
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Other Published Material
Invasiveness?
Total Points
17 Total Score A
2.2 ?Local rate of spread with no management A. Increases 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 A. High Other Published Material
2.6 ? Potential for natural long-distance dispersal A. Frequent Other Published Material
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
C. Limited Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
B. Moderate 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? A Reviewed Scientific Publication
Identify ecosystem processes impacted:

Slows water flow. Causes increased sedimentation and nutrient loading.


Sources of information:

De Winton, M.D. and J.S. Clayton. 1996. Aquatic Botany 53(1-2):31-45; Barko, J.W. and R.M. Smart. 1980. Freshwater Biology 10:229-238


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

Reduces the abundance and diversity of native plant seeds in lake bottoms.


Sources of information:

De Winton, M.D. and J.S. Clayton. 1996. Aquatic Botany 53(1-2):31-45


Question 1.3 Impact on higher trophic levels? A Other Published Material
Identify type of impact or alteration:

Reduces oxygen level. Poor fish habitat. Fall River area with infestation has fewer trout than areas with native vegetation.


Sources of information:

www.wa.gov/ecology/wq/plants/weeds/egeria.html; DiTomaso and D. Spencer-Observational


Question 1.4 Impact on genetic integrity? D Other Published Material

None Only male flowers in US.


Sources of information:

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

Can readily invade an undisturbed aquatic site once introduced. Adapted to most slow or still water bodies in California.


Sources of information:

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

Once introduced, it spreads very rapidly in aquatic systems.


Sources of information:

DiTomaso, Spencer and Anderson-Observational


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

Probably continuing to spread in state, but some control effort has slowed the statewide spread.


Sources of information:

DiTomaso, J.M. and E.A. Healy. 2005. Weeds of California. DANR (pre-print)


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

Sources of information:

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

Used as aquarium and pond ornamental. Also moved by boats from on body of water to another.


Sources of information:

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

Fragments can move downstream long distance and produce new plants.


Sources of information:

DiTomaso, J.M. and E.A. Healy. 2005. Weeds of California. DANR (pre-print)


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

Common weed throughout much of the world, including Australia.


Sources of information:

Parsons, W.T. and E.G. Cuthbertson. 1992. Noxious Weeds of Australia. Inkata Press, Sydney


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

Found throughout much of California and the US, primarily in cool to warm freshwater ponds, lakes, reservoirs and slowly flowing streams and sloughs. Earliest report in US was in 1893.


Sources of information:

DiTomaso, J.M. and E.A. Healy. 2005. Weeds of California. DANR (pre-print); Hoshovsky, M. and L. Anderson. 2000. Egeria densa. In, Invasive Plants of Californias Wildlands. CalEPPC. UC Press, Berkeley; www.wa.gov/ecology/wq/plants/weeds/aqua002.html


Question 3.2 Distribution/Peak frequency? B Other Published Material
Describe distribution:

One of the most common non-native submerged aquatic plants in California.


Sources of information:

Hoshovsky, M. and L. Anderson. 2000. Egeria densa. In, Invasive Plants of Californias Wildlands. CalEPPC. UC Press, Berkeley


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less No
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. No
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere Yes
Resprouts readily when cut, grazed, or burned Yes
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, reservoirsB, 20% - 50%
Aquatic Systemsrivers, streams, canalsC, 5% - 20%
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 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 woodland
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): C
Distribution (highest score): B

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest
  • Modoc Plateau
  • Sierra Nevada East