Plant Assessment Form

Myoporum laetum

Common Names: ngaio tree; false sandalwood; mousehole tree

Evaluated on: 9/28/04

List committee review date: 11/02/2005

Re-evaluation date:

Evaluator(s)

Peter J. Warner
California Department of Parks and Recreation; CNPS; Cal-IPC
P. O. Box 603, Little River, CA 95456
(707) 937-9172 (w); (707) 937-278 (h)
pwarner@mcn.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? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Impact?
Four-part score UACD Total Score
B
1.2 ?Impact on plant community A. Severe Other Published Material
1.3 ?Impact on higher trophic levels C. Minor Other Published Material
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Reviewed Scientific Publication
Invasiveness?
Total Points
14 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 C. Stable Observational
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)
A. Widespread Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. 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:

The species accumulates dead twigs, rendering it flammable (1). However, no documentation that this species has actually contributed to the spread of wildland fires, or to a change in fire intensity or frequency. insuffucient documentation of impact on fire regimes


Sources of information:

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

Competition for light, moisture, nutrients in moist habitats, displacing native species of trees, shrubs, herbs, and forming monocultures (1, 2, 3, 4, 5, 6). Personal observations, personal communications about Myoporum populations in California state parks.


Sources of information:

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

Potentially toxic to wildlife, based on published accounts of toxicity to livestock, including sheep and cattle (1, 2, 3). Attractiveness of fleshy fruits could contribute to wildlife poisoning, although fruits are less toxic than foliage (2). Foliage is likely to be ingested by some herbivores, such as deer, and fruit is toxic to some degree, potentially injuring birds.


Sources of information:

Question 1.4 Impact on genetic integrity? D Other Published Material

None likely. This is the only species in the family that grows without human assistance in California (1). No closely related species native to California.


Sources of information:

1. Hickman, JC (editor). 1993. The Jepson Manual: Higher Plants of California (Third Printing, with corrections). University of California Press, Berkeley. p. 765.


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

Results of germination trials (1) suggest that Myoporum requires moisture and light for optimal germination rates. Myoporum's 4 seeds/fruit are encased in a hard endocarp; cutting of this endocarp resulted in no difference in germination, suggesting that physical disturbance is not necessarily needed for seed germination. However, germination does not occur if the 4-seeded unit is retained within the fleshy drupe. Reports indicate that this species spreads from landscape plantings into adjacent moist areas, or where the water table may be near to the soil surface (2, 3, 4, 5, 6). Under these conditions, Myoporum appears to need little physical disturbance. In light of these observations, the posted score here is conservative.


Sources of information:

1. Burrows, CJ. 1996. Germination behaviour of seeds of the New Zealand woody species Melicope simplex, Myoporum laetum, Myrsine divaricata, and Urtica ferox. New Zealand Journal of Botany 34(2):205-213.
2. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation.
3. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation.
4. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org
5. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785
6. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net


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

Spreads from landscape plantings at central and southern California coastal state parks, where campground plantings of Myoporum are common. Also observed spreading occasionally from landscape plantings in northern coastal California. No indication or observations that the spread is rampant; a conservative estimation of spread is less than doubling in area over 10 years.


Sources of information:

1. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation.
2. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation.
3. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org
4. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785
5. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net


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

No quanified information on total area infested. The species has been planted widely for many years, and is currently being removed in several state parks. A qualified estimate, based on this species' widespread use in landsapes, and the current rate of removal.


Sources of information:

Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net


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

Fruit is a fleshy drupe enclosing a stony endocarp containing 1-4 seeds (1, 2). Seeds removed from fruit and endocarp tend to germinate more readily than those remaining contained in the endocarp (1, 2). The endocarp may be an adaptation for seed longevity, and could account for long-lived seed banks. Abundance of seed production is unclear: > 1000 seeds/square meter? Seeds will definitely germinate in suitable habitat in California.


Sources of information:

1. Burrows, CJ. 1996. Germination behaviour of seeds of the New Zealand woody species Melicope simplex, Myoporum laetum, Myrsine divaricata, and Urtica ferox. New Zealand Journal of Botany 34(2):205-213.
2. DiTomaso, J, and E. Healy. (in production). Weeds of California and Other Western States (unpublished).


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

Nurseries sell this species, seed catalogues advertise it, and the City of Los Angeles identifies it as a desirable street tree (1). Calif. Dept. of Parks and Recreation and other agences planted this tree widely in coastal areas over the past century


Sources of information:

1. City of Los Angeles website. 2004. http://www.lacity.org/BOSS/streettree/MyoporumLaetum.htm


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

Sources of information:

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

Native to New Zealand coastal forests (1, 2). Cited (2) as invasive in Hawai'i, but not by USDA (3) in that state. Otherwise, no reports from anywhere other than the California coast, where it apparently invades habitats other than coastal forests. Due to frost sensitivity, and need for moisture, this species would probably not pose invasive threat to interior California, or the more northern coast - this may account for its scarcity as an invasive plant north of the SF Bay Area.


Sources of information:

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

Central and southern California coast, especially moist to wet habitats, including coastal scrub, riparian woodland and scrub, salt, brackish, and freshwater marshes, dunes/strand where moisture is available (1, 2, 3, 4, 5, 6, 7)


Sources of information:

1. Kitz, J. 2000. Myoporum laetum. in Bossard, CC, JM Randall, and MC Hoshovsky. Invasive Plants of Californias Wildlands. University of California Press, Berkeley. pp. 246-249.
2. DiTomaso, J, and E. Healy. (in production). Weeds of California and Other Western States (unpublished).
3. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation.
4. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation.
5. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org
6. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785
7. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net


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

more common in these ecological types from SF Bay Area south (1, 2, 3, 4, 5) conservative estimates, lacking any quantified data.


Sources of information:

1. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation.
2. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation.
3. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org
4. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785
5. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less No
Dense infestations produce >1,000 viable seed per square meter Unknown
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 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: 4
Total unknowns: 2
Total score: B?

Related traits:

Fruit is a fleshy drupe enclosing a stony endocarp containing 1-4 seeds. Seeds removed from fruit and endocarp tend to germinate more readily than those remaining contained in the endocarp. The endocarp may be an adaptation for seed longevity, and could account for long-lived seed banks.

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
DunescoastalC, 5% - 20%
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrubC, 5% - 20%
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 prairieD, < 5%
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampC, 5% - 20%
Riparian and Bottomland habitatriparian forest
riparian woodlandD, < 5%
riparian scrub (incl.desert washes)D, < 5%
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): A
Distribution (highest score): C

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest
  • Sierra Nevada East
  • Mojave Desert