Plant Assessment Form

Myosotis latifolia

Synonyms: Myosotis sylvatica [misapplied in older California references]

Common Names: common forget-me-not; wood forget-me-not; broadleaf forget-me-not

Evaluated on: 12/13/04

List committee review date: 11/02/2005

Re-evaluation date:

Evaluator(s)

Jim Bromberg/ Biological Science Technician
Point Reyes National Seashore
1 Bear Valley Road, Point Reyes Station CA 94956
(415) 464-5231
James_Bromberg@nps.gov
Peter J. Warner / ecologist
California State Parks
P. O. Box 603, Little River, CA 95456
707-937-9172; 707-937-2278
corylus@earthlink.net

List commitee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

There is no information on Myosotis sylvestris, and little on M. latifolia, so perhaps this PAF should cover both of them. I changed the level of documentation (and citation format) on 2.4 from anecdotal to "other published". Because the weeds book isn't out yet, I wasn't sure if it can be counted as reviewed yet.- E. Brusati

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 U Reviewed Scientific Publication
Impact?
Four-part score UBUD Total Score
C
1.2 ?Impact on plant community B. Moderate Observational
1.3 ?Impact on higher trophic levels U. Unknown Observational
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
15 Total Score B
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)
A. High Other Published Material
2.5 ?Potential for human-caused dispersal A. High Observational
2.6 ? Potential for natural long-distance dispersal B. Occasional Observational
2.7 ?Other regions invaded C. Already invaded Observational
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. Low Reviewed Scientific Publication

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:

unknown


Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
B Observational
Identify type of impact or alteration:

reduction in native ground cover (1). Myosotis is an invader of the understory along roads and trails, and once established, spreads into less disturbed adjacenty native plant communities (2). 1. At Muir Woods National Monument, it was found that M. latifolia was the dominant forest floor cover prior to removal. Following removal, there was a noticeable increase in uncommon native plants including trillium, clintonia, fetid-adderstongue, starflower, etc. (Monroe)


Sources of information:

Email from Mia Monroe, Muir Woods National Monument (National Park Service). mia_monroe@nps.gov
2. Warner, PJ. Personal observations, 1996-2005. Marin, Sonoma, Mendocino, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

Reduction of habitat for invertebrates, small mammals and birds Muir Woods National Monument has experienced rebounds of plant diversity after removing monocultures of forget-me-nots. Since different plants are often required at various stages of the life cycle for different animals, it is suspected that habitat for many animals may be reduced by M. latifolia, although no known research has been done at this point. [Hypothetical arguments should be discarded. - PJW]


Sources of information:

email from Mia Monroe, Muir Woods National Monument


Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

Extremely unlikely to impact the one native forget-me-not, Myosotis laxa. Regional distributions and habitats of M. laxa and M. latifolia do not overlap, so potential for hybridization would seem to be low.


Sources of information:

Hickman, J. (editor). 1993. The Jepson Manual: Higher Plants of California.


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

Myosotis will move in after disturbance by fire (1), and mowing, and trail maintenance, etc. (2). Point Reyes National Seashore experienced Myosotis spreading after the Mount Vision fire of 1995. In some shaded areas, populations of Myosotis were observed to be 75 to 100% cover in the three years following the fire.


Sources of information:

1. U. S. Dept. of the Interior, Pt. Reyes National Seashore. 1998. Vision Fire Vegetation Monitoring Final Report 1996-1998.
2. Warner, PJ. Personal observations, 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Del Norte, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

Aggressive. Infestations expand very quickly from one plant (2). Muir Wood National Monument has experienced M. latifolia growing and taking over partly shaded and moist areas especially where other non-natives have been removed or soil has been disturbed. While actual quantitative rates of spread have not been determined, staff at MWNM consider it to spread aggressively.


Sources of information:

1. Email from Mia Monroe, Muir Woods National Monument
2. Warner, PJ. Personal observations, 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Del Norte, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

Increasingly common. I have no prior data, but based on reports of distributions in the Jepson Manual and the CalFlora Database, I'd estimate that this plant is expanding its range (2). [M. latifolia] has become an increasingly common site along trails of the Monterrey Bay area (1).


Sources of information:

1. Weed Control By Species:Elkhorn Slough National Estuarine Research Reserve (October 2000). http://www.elkhornslough.org/plants/weeds.PDF
2. Warner, PJ. Personal observations, 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Del Norte, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

Reproduces by seed and vegetatively by fibrous creeping roots. Seeds can remain viable over long periods of time (1).


Sources of information:

1. Di Tomaso, J,and E. Healy. in prep. Weeds of California. as yet unpublished.


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

Seeds available at seed distributors and nurseries; seeds stick to hikers pant legs. Based on distribution of this species along trails and roads, the evidence is fairly convincing that human activities can be implicated in its dispersal (2). Muir Woods believes that seeds were scattered intentionally in the Redwood Creek watershed by local garden clubs. They additionally believe that seeds have been further distributed by attachment to hikers legs and transport throughout the trail system (1). These seeds are available at most seed distributor websites. Mowing and other road- and trailside maintenance activities can also spread seeds (2).

Considering the dispersal mechanisms noted above, and the dominance of this species along roads and trails, I'd hypothesize that humans account for the most of the seed dispersal for this species (2).


Sources of information:

1. email from Mia Monroe, Muir Woods National Monument
2. Warner, PJ. Personal observations from 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Del Norte, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

unknown if there are any animal dispersal mechanisms but may be dispersed by water. The fruits have hooked appendages that cling to fur; most animals probably do not range more than 1 km from the site of seed attachment, but some do (2). Muir Woods National Monument has found populations of M. latifolia downstream from other populations and suspect that either seeds or root fragments may be carried downstream by high water events (1).


Sources of information:

1. email from Mia Monroe, Muir Woods National Monument
2. Warner, PJ. Personal observations, 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Del Norte, Humboldt Counties. 707-937-2278/corylus@earthlink.net


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

Only listed as invasive in the U. S. in California (1).


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.


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

It is know to occur mostly in forested riparian areas of California.
Sporadically very invasive in Calif. north coast forests and riparian woodlands, especially impacting forest edges, such as along trails and roads; very uncommon outside moist, shady, generally coastal habitats (4). The USDA reports Myosotis latifolia occurring in approximately 12 counties in California, mostly coastal counties or directly adjacent to the San Francisco Bay. Muir woods reports it occurring on the forest floor in the Redwood Creek Watershed. I have personally observed it in Point Reyes National Seashore and Golden Gate National Recreation Area along hillsides of forested creeks and streams. It is reported in Marin Flora to be abundantly naturalized in moist places with high shade, especially under redwoods.


Sources of information:

USDA, NRCS. 2004. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
email from Mia Monroe,
Howell, J. T. 1970. Marin Flora: manual of the flowering plants and ferns of Marin County, California. University of California Press. Berkeley, CA.
4. Warner, PJ. Personal observations, 1996-2005. San Mateo, Marin, Sonoma, Mendocino, Humboldt Counties. 707-937-2278/corylus@earthlink.net


Question 3.2 Distribution/Peak frequency? C Reviewed Scientific Publication
Describe distribution:

unknown


Sources of information:

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 Yes
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination Unknown
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: 7
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 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 forestD, < 5%
riparian woodlandD, < 5%
riparian scrub (incl.desert washes)U, Unknown
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forestU, Unknown
North Coast coniferous forestC, 5% - 20%
closed cone coniferous forestD, < 5%
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): C

Infested Jepson Regions

Click here for a map of Jepson regions

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