Plant Assessment Form

Chrysanthemoides monilifera ssp. monilifera

Synonyms: Osteospermum moniliferum

Common Names: boneseed; Higgin's curse; jungle flower;

Evaluated on: 30-Dec-16

List committee review date: 26/01/2017

Re-evaluation date:


Lynn Sweet/Associate Research Specialist
University of California, Riverside
75-080 Frank Sinatra Dr., Palm Desert, CA 92211
Mona Robison/Science Program Manager

List commitee members

Jutta Burger
Naomi Fraga
Denise Knapp
Chris McDonald
Ron Vanderhoff
John Knapp
Elizabeth Brusati

General Comments

From the evaluator:
The subspecies of Chrysanthemoides that we have here in California, according to Calflora and local experts, is Chrysanthemoides monilifera ssp. monilifera, which is referred to as "boneseed." Chrysanthemoides monilifera ssp. rotundata is the subspecies that Australians refer to as "bitou bush" therefore this common name should not be used for this species.
Key differences from CRC Weed Management Guide:
"In contrast to the closely related bitou bush (Chrysanthemoides monilifera
ssp. rotundata) which has a sprawling habit, boneseed is an erect shrub."
Information used to prepare the PAF should be based on "ecological impacts on the species' behavior in ecosystems within the state; however, species behavior elsewhere within similar ecosystems can be used when a non-native species previously unknown within a state is newly discovered and requires judgement as to whether it qualifies for rapid response (Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands)." Impacts in California are currently low because this species is early in the invasion curve. Observed impacts from the only two extant CA populations (Orange County) are uncertain, as the species currently covers only about 1 acre gross and is primarily in urban edge habitat. However, since the species has naturalized in California impacts from other regions were used to assess the potential impacts.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? Alert
Documentation? 3.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Reviewed Scientific Publication
Four-part score CBCD Total Score
1.2 ?Impact on plant community B. Moderate Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels C. Minor Reviewed Scientific Publication
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
Total Points
17 Total Score A
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 B. Increasing less rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal A. Frequent Reviewed Scientific Publication
2.7 ?Other regions invaded A. Invades 3 or more ecological types Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
C. Limited Other Published Material
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low 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? C Reviewed Scientific Publication
Identify ecosystem processes impacted:

There is some disagreement about whether this species increases fire frequency or intensity, as listed on the (Australia) Queensland Biosecurity site, but fire can kill adult plants, seedlings and seeds, and has been used to control the species, according to a recent status review (1, 2). This species does regenerate readily after fires in some situations (3).

No other information was found specifically for the subspecies, C. monilifera ssp. monilifera, however, the more well-studied subspecies, C. monilifera ssp. rotundata has some documented impacts on soils, listed below.

Nutrient and mineral dynamics may be impacted by C. monilifera ssp. rotundata, as rates of decomposition between this species and native sclerophyllous species in Australia were shown to be very different, where the former cycles much faster. (4)
Nitrogen cycling was shown to be altered by this species in a separate study by the same authors in Australia. (5)
Allelopathic properties were also found for this plant, and the non-polar chemicals were isolated from plant leaves, which could interfere with plant-microbe interactions. The authors hypothesized that the addition of these chemicals to the soil could drive community changes. (6)

Sources of information:

(1) Weiss et al. (2008)
(2) Queensland Biosecurity Edition
(3) Parsons and Cuthbertson (2001)
(4) Lindsay & French (2004)
(5) Lindsay & French (2005)
(6) Ens et al. (2009)

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

Observed impacts from the only two extant California populations (Orange County) are uncertain, as the species currently covers only about 1 acre gross and is primarily in urban edge habitat. (1)

This species has been known to form monocultures and reduces diversity of above-ground vegetation as well as the seedbank in studies in Australia. (2)
The species competes well with existing vegetation and can overtop and dominate the native community.
Both this and the other subspecies present in Australia (rotundata) are Weeds of National Significance due to threats including to species of special concern, including 14 at risk, as reported, solely due to this species. (3,4)
There is some evidence that this species may exude allelopathic compounds that suppress growth by other species. (5)

Sources of information:

(1) Vanderhoff, R. 2017. Personal communication.
(2) Thomas et al. (2005)
(3) Weiss et al. (2008)
(4) Parsons, W.T., & Cuthbertson E.G.. (2001)
Al Harun et al. (2014)

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

This species is known to reduce the amount of preferred forage plants for native bird species post-invasion. (1)
This species does provide forage for some native birds and marsupials in Australia, as well as some feral and farm species. (2)

Sources of information:

(1) Parsons, W.T., & Cuthbertson E.G.. (2001)
(2) Weiss et al. (2008)

Question 1.4 Impact on genetic integrity? D Other Published Material

There are no native species in the Chrysanthemoides genus in California. (1)
This species is in the Calenduleae Tribe within Asteraceae, and the other species in this tribe are also not present in California (primarily African/South African origin). (1,2)

Sources of information:

(1) Calflora 2016

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

California populations are still emergent, but plants are primarily in semi-cultivated habitats with some plants receiving supplemental irrigation or urban runoff. I would define the CA infestations as primarily disturbed habitat at present. (1)

For the species in Australia, Weiss 2008, states that while fire promotes seedling emergence, no disturbance is necessary and this species can readily colonize disturbed sites. (2)
This species is in fact suppressed by soil cultivation, trampling and grazing. (3)


Sources of information:

(1) Vanderhoff, R. 2017. Personal communication.
(2) Weiss et al. (2008)
(3) Parsons, W.T., & Cuthbertson E.G.. (2001)

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

At the principal/largest infestation (Aliso Canyon, South Orange County) observations only span four years since the detection. However, plants were mature and well established, indicating a best guess of the colony being extant for 10-15 years. At present the colony occupies a gross area of .75 acre.
One population has spread 500-600 meters in 10 years, noted to be a moderate rate of spread for a woody perennial shrub.
Management notes for Australia for this species warn land managers that this species can expand reestablish after fire in certain cases, and the population can "expand as it quickly re-established a massive seedbank."
"No management activity has been planned or executed at the two Orange County colonies. The plants are spread across a multitude of private property owners as well as city and probably state property."
A case study detailed in the management guide: "Boneseed expanded its range rapidly after bushfires in 1985 in the You Yangs Regional Park, south-west of Melbourne. Before the fires, boneseed was scattered throughout the park. The fires were widespread, burning 85 per cent of the park, and they triggered the mass germination of huge numbers of boneseed seedlings. Within three years of the fire, the boneseed infestation became dense and widespread in the You Yangs, and now impacts upon 1300 hectares of the 2000 hectare park. Boneseed now dominates the middle-storey vegetation in the areas that were burned." (2)
It is thought to have been introduced to mainland Australia approximately 1850 as a garden plant, and in 1981 a survey in Victoria found 72,000 ha of scattered plants and an additional 6,0000 ha of moderate to densely infested area. Also introduced to Tasmania and now "grows abundantly on parts of the North Coast" as well as occurring in several other regions. (3)

Sources of information:

(1) Vanderhoff, R. 2017. Personal communication.
(2) CRC (2003)
(3) Parsons, W.T., & Cuthbertson E.G. (2001)

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

Information from local expert R. Vanderhoff: The first US detection was at Palomar College (San Diego County) in 1990, a population that may or may not still be extant. The species is not widespread in the state and is concentrated near the coastline in Orange County.
In terms of management activities, "No management activity has been planned or executed at the two Orange County colonies. The plants are spread across a multitude of private property owners as well as city and probably state property. " (1)


Sources of information:

(1) R Vanderhoff, personal communication (1/9/17)

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

This species is an aster, the subspecies evaluated here is capable of up to 8 seeds per inflorescence (head). Based on the number of heads produced per year, estimated at up to 50,000 seeds per plant per year. Noted that bees and other visitors "may not be essential for pollination" (implying that selfing is possible). 50% germination rate, seeds set into the seedbank persist and are viable for at least 3 years, depending on depth of burial. Vegetative reproduction is possible via layering. Fragmentation and dispersal does not seem likely based on the habitat. Adventitious budding allows resprouting after herbivory or fire (light). (1)

Sources of information:

(1) Weiss et al. (2008)

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

The pathway of introduction of C. monilifera ssp. monilifera in California is unknown, but a closely related/non-invasive species, C. incana, is marginally in the landscape trade currently. My suspicion is that horticulture would be the likely point if introduction, especially since the first CA detection (now extirpated?) was adjacent to the horticulture department at a college in San Diego County (1).

There has been some noted dispersal via dumping of garden refuse in Australia; however it is now illegal to sell there, limiting this mechanism of spread. It was also used for "sandbinding" (sand stabilization) in many areas, promoting spread (now also prohibited). Infestations are noted to be centered around population centers in Tasmania.
Contaminated gravel has been implicated in regional spread in some areas, and there is some mention of dispersal via machinery (3); however, the hard-seeded species does not seem specifically amenable to dispersal this way over any other species. The key would be movement of contaminated soils, not necessarily the use of machines.

Sources of information:

(1) R Vanderhoff, personal communication (1/9/17)
(2) Weiss et al. (2008)
(3) Brougham et al. (2006)

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

Animals are implicated in "readily" spreading the fleshy fruit in Australia long distances, including sheep, cattle, non-native foxes, birds (emu), and several large marsupials. (1,2)

Sources of information:

(1) Brougham et al. (2006)
(2) Parsons, W.T. & Cuthbertson, E.G.. (2001)

Question 2.7 Other regions invaded? A Reviewed Scientific Publication
Identify other regions:

Noted in Australia as growing in a wide range of climatic conditions, in sandy/medium-textured soils, and being tolerant of saline conditions and salt spray. Noted as invading "malee scrub", open eucalypt-dominated forests, and coastal fringe. These may be analagous to coastal sage scrub, oak or other open woodlands, and coastal bluffs. (1)
Noted as occurring with both a canopy, and in the open, and invading a "range of communities" in Australia. It is "intolerant of water-logged soils however it can grow along watercourses and in estuarine areas." "Boneseed It is capable of growing in coastal ecosystems such as dune forests and woodlands, dune scrub, estuarine areas, heathlands, headlands, grasslands and dry sclerophyll forests. It also occurs in a range of communities further inland, including mallee shrubland and open eucalypt woodland." These also map similarly to coastal bluffs, coastal sage scrub, estuarine areas, grasslands, and perhaps interior oak woodlands and inland sage scrub. (2)

Sources of information:

(1) CRC (2003)
(2) Weiss (2008)

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

Specimens in the Consortium of CA Herbaria are noted to be from coastal sage scrub and coastal bluff communities. The first specimens were collected in 1990 in San Diego (Palomar) and Orange County (Irvine) near colleges. The Palomar specimen was noted to be located on a hillside northeast of Palomar College.(1) The first reports of C. monilifera ssp. monilifera naturalizing further away from plantings were in 2013 in Orange County (2). Although in Australia this species occurs on dunes (3), no specimens were noted as being present on dunes.

Sources of information:

(1) Consortium of California Herbaria (Accessed 1/8/17)
(2) Calflora database (Accessed 1/8/17)
(3) Brougham et al. 2006

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

Plants are distributed on coastal bluffs in Aliso Canyon, including the periphery of dune edges, where heavy foot traffic may be keeping this and other plants from establishing on the dunes. (1)
San Diego herbaria specimens note coastal sage scrub habitat. (2)
This plant is found in discrete, not ubiquitous populations, with <5% frequency in all of coastal bluff and coastal sage scrub habitats. (1)

Sources of information:

(1) R Vanderhoff, personal communication (1/9/17)
(2) Calflora (accessed 1/9/17)

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 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: 9
Total unknowns: 1
Total score: A?

Related traits:

Vegetative reproduction noted as via layering. Information from Weiss (2008).

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
Scrub and Chaparralcoastal bluff scrubD, < 5%
coastal scrubD, < 5%
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
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): D

Infested Jepson Regions

Click here for a map of Jepson regions