Plant Assessment Form

Lythrum hyssopifolium

Synonyms: L. adsurgens, L. hyssopifolia

Common Names: hyssop loosestrife; grass poly; hyssop lythrum

Evaluated on: 12/29/04

List committee review date: 11/02/2005

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

List commitee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

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

no information


Sources of information:

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

Could outcompete native species early in succession. Other species would outcompete L. hyssopifolium at later successional stages.
In California, I've never seen a serious infestation of this plant, and given its poor long-term competitive ability (1), and preference for disturbed environments, I don't think that this plant has more than minor impacts on wild, native plant communities (3) Highly competitive during early stages of succession but lacks long-term competitive ability (1). Because of specific habitat requirements, is less likely than purple loosestrife to displace native species (2). This species may be more invasive elsewhere, but my observations don't support this plant being considered a serious weed of wildlands (3).


Sources of information:

1. Callaghan D.A. 1998. Biological Flora of the British Isles: Lythrum hyssopifolium L. Journal of Ecology 86: 1065-1072
2. Johnson, M. T., and C. J. Rothfels. 2001. The establishment and proliferation of the rare exotic plant, Lythrum hyssopifolia, Hyssop-leaved Loosestrife, at a pond in Guelph, Ontario. Canadian Field-Naturalist. 115(2): 229-233.
3. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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

no information


Sources of information:

Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

none no native Lythrum in California


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 Reviewed Scientific Publication
Describe role of disturbance:

Seems to require disturbance to open up bare areas for colonization (1,2). However, Lythrum h. does pioneer on seasonally flooded and silted sites, thus natural disturbance is also a factor in germination and establishment (3).


Sources of information:

1. Callaghan 1998
2. Johnson and Rothfels 2001
3. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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

In Ontario, increased from 100 plants with 426 stems to 1556 plants with 2090 stems in one year (1).


Sources of information:

1. Johnson and Rothfels 2001
2. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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

Most likely stable. This species was probably introduced to California long ago, and by now it has probably invaded most suitable habitats (1)


Sources of information:

1. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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

Summer annual or biennial (1). Can cross-fertilize but usually self-pollinates. Flowers April - October (1). Produces many seeds and shoots grow from adventitious roots (1, 2). Large individuals can produce 75, 000 seeds (3). Long-lived seed bank (2); seeds can survive 14 years in lab (1).


Sources of information:

1. DiTomaso J.M., and E.H. Healy. 2003 Aquatic and Riparian Weeds of the West. University of California Agricultural and Natural Resources Publication 3421. University of California. Pgs. 171-175.
2. Johson and Rothfels 2001
3. Callaghan 1998.


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

"Human activities" (1). Seeds transported on shoes or possibly boats.


Sources of information:

1. DiTomaso and Healy 2003
2. Callaghan 1998


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

Seeds caught in mud on birds' feet (1, 1) or fur and feet of mammals (D). Possible transport by water.


Sources of information:

1. Callaghan 1998
2. DiTomaso and Healy 2003


Question 2.7 Other regions invaded? C
Identify other regions:

Native to Europe, found on every continent except Antarctica (1). Recorded in North America in 1815 (1). Present in Washington and Oregon (2).


Sources of information:

1. Johson and Rothfels 2001
2. DiTomaso and Healy 2003


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

Common in seasonal wetlands, ditches,and crops, especially rice fields. Tolerates some salinity but sensitive to heavy frost. Present throughout California except in Great Basin and deserts, to 1600m (1).


Sources of information:

1. DiTomaso and Healy 2003
2. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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

Very common in marshes and other wetlands; not conspicuous, but often present in seasonally moist swales in grassland, scrub, and some woodlands. I have compiled numerous plant lists throughout northern California, and most of them include Lythrum h. (1).


Sources of information:

1. Warner, PJ. Personal observations, 1990-2005. San Mateo, Marin, Sonoma, Napa, Mendocino, Plumas, Sacramento, Del Norte, Humboldt, and other counties. 707-937-2278/corylus@earthlink.net


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 Unknown
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 Yes
Resprouts readily when cut, grazed, or burned Unknown
Total points: 10
Total unknowns: 2
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 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 prairieB, 20% - 50%
valley and foothill grasslandD, < 5%
Great Basin grassland
vernal poolC, 5% - 20%
meadow and seepB, 20% - 50%
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampA, > 50%
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): B
Distribution (highest score): A

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
  • Southwest