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PRE — Plant Risk Evaluator

Cordyline australis -- California

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Evaluation Summary


photo by Jade

Evaluation Date:  2020-02-11

Screener:  Lynn Sweet
 
Plant:  Cordyline australis
Common Name(s):
Cabbage palm, Cabbage tree

State:  California

PRE Score:  7
Questions Answered:  20
Screener Confidence (%):  64

Executive Summary

This is a monocotyledonous tree native to New Zealand, which has been planted worldwide as an ornamental. It is capable of setting a large amount of seed but this reproduction may be limited by environmental conditions and a need for out-crossing to set seed. The plant does not appear to reproduce via the underground rhizome. There is a lack of information regarding the invasiveness of the species overall in any area where it has naturalized and particularly in the region of interest. Many international "wild"rec ords appear to be of plantings. It is adapted to fire, but does not appear to promote it, it does not pose threats to health and it seems to lack evidence of impacts on native systems where it has naturalized.

Climate Matching Map

https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B0%5D=06&ma…
Attachment Size
climatematch-cordyline_australis-california-20251031.pdf (1.14 MB) 1.14 MB

1. Question 1

Yes
1
Very High
The tree is native to New Zealand, but has naturalist in North America, Europe, and southeast Australia. (GBIF)
USDA GRIN does not list any naturalized areas as of this evaluation.
Secretariat, GBIF. 2016. “GBIF Backbone Taxonomy”. Copenhagen, Denmark: GBIF Secretariat. https://www.gbif.org/.

2. Question 2

Yes
2
Very High
There are records in 13 counties in the region of interest, California, USA, the highest number (16) being in Marin County. (Calflora)
Some of the occurrences in southeast Australia and Tasmania are in areas that match the climate of the region of interest, as well as a few noted occurences in Sicily, Spain and France. (GBIF).
Calflora. 2016. “Calflora California Wild Plant Database”. Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/.
Secretariat, GBIF. 2016. “GBIF Backbone Taxonomy”. Copenhagen, Denmark: GBIF Secretariat. https://www.gbif.org/.

3. Question 3

No
0
Low
The plant is an "emerging environmental weed" in Victoria, Australia (Queensland Government). Information from the study region of interest is noted in Q4, below.
Central, Lucid. 2020. “Environmental Weeds of Australia: Cordyline Australis (G. Forst.) Endl. Fact Sheet ”. https://keyserver.lucidcentral.org/weeds/data/media/Html/cordyline_aust….

4. Question 4

No
0
Low
The plant is an "emerging environmental weed" in Victoria, Australia (Queensland Government).
The populations in California as yet have not been described as invasive, though there are ~53 observations currently listed, with many listing many naturalized plants. (Calflora)
"Habitat types invaded as noted in Redwood National Park suggest that disturbance may facilitate germination and growth, but my observations suggest that disturbance post-digestion is not necessary for germination." Cal-IPC PAF summary of Personal Communication from Andrea Williams
Calflora. 2016. “Calflora California Wild Plant Database”. Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/.
Williams, Andrea. 2005. “Personal Communication. Andrea Williams. 2005. Observations at Redwood National Park”. https://www.cal-ipc.org/plants/paf/cordyline-australis-plant-assessment….

5. Question 5

No
0
Very Low
No other Cordyline species were noted as invasive in a similar climate.
Cordyline fructosa is fairly pan-tropical but is considered introduced to Hawaii, which is not a similar climate to the area of interest. (CABI)
Rojas-Sandoval, Julissa. 2007. “CABI Invasive Species Compendium”. https://www.cabi.org/.

6. Question 6

No
0
Medium
Only about half of the native range in New Zealand matches the climate of the region of interest. Of the other regions in which there are records, the following do not match the climate:
South America, inland-South Africa, England, Scotland, Northern Europe, Hawaii, coastal southeastern Australia and eastern Tasmania. (GBIF)
The following areas match the climate:
California (coastal) USA, southern Europe and the Mediterranean, occurrences on the South Island of New Zealand, and southeast Australia (some) and western Tasmania. (GBIF)
Secretariat, GBIF. 2016. “GBIF Backbone Taxonomy”. Copenhagen, Denmark: GBIF Secretariat. https://www.gbif.org/.

7. Question 7

No
0
Medium
Observed to establish as very minor component of north coast coniferous forests in Sonoma County in and adjacent to Salt Pt. State Park; does not appear to alter native composition of forest. (Warner)
Observations do not indicate any major alteration of community composition, but potential to add a new layer (sub-canopy) in small stands, or to alter riparian zone composition. (Williams)
Williams, Andrea. 2005. “Personal Communication. Andrea Williams. 2005. Observations at Redwood National Park”. https://www.cal-ipc.org/plants/paf/cordyline-australis-plant-assessment….
Warner, Peter. 2005. “Personal Communication. Peter Warner, Observations at Salt Pt. State Park and Kruse Rhododendron Preserve, Sonoma Co”. https://www.cal-ipc.org/plants/paf/cordyline-australis-plant-assessment….

8. Question 8

No
0
Low
This plant does have a mass of leaves, but they are on year-round and it is unlikely they would promote fire, since the lower trunk is bare in maturity. (Missouri Botanical Garden)
The species is adapted to fire and can resprout from a rhizome. It is listed as Moderately flammable ("Most of these species produce heavy accumulations of flammable litter and elevated dead material, and/or have flammable green foliage. Not recommended for green breaks or for planting in defensible space") (McMahon & Pearce 2005; this information was also found in various brochures)
No evidence that the species promotes fire and transforms the plant community.
McMahon, S., and H. Pearce. 2005. “Flammability of Native Plants”. Open Space 63: 20-21. https://www.researchgate.net/publication/300066803_Flammability_of_nati….

9. Question 9

No
0
Medium
The plant has been harvested and consumed by Maori people, indigenous people of New Zealand and has been investigated for food ingredient production (Harris & Mann 1994).
Harris, W., and J. D. Mann. 1994. “Preliminary Investigation of the Suitability of Cordyline Australis (Asphodelaceae) As a Crop for Fructose Production”. New Zealand Journal of Crop and Horticultural Science 22. https://www.tandfonline.com/doi/abs/10.1080/01140671.1994.9513856.

10. Question 10

No
0
Medium
The plants are often single trunked or branching up high. It is unlikely that this would produce a thicket. Noted that if one coppices the tree that would increase branching, but this wasn't noted to happen naturally.
No references cited.

11. Question 11

No
0
Medium
The species does produce underground shoots (rhizomes) that could technically sprout new plants, but I found no documentation of this whatsoever, even as a propagation technique.
Harris, W., and J. D. Mann. 1994. “Preliminary Investigation of the Suitability of Cordyline Australis (Asphodelaceae) As a Crop for Fructose Production”. New Zealand Journal of Crop and Horticultural Science 22. https://www.tandfonline.com/doi/abs/10.1080/01140671.1994.9513856.

12. Question 12

No
0
Medium
While the species does produce a large underground rhizome and propagation may be done via aboveground stem cuttings, there was no documentation of fragments detaching and dispersing.
No references cited.

13. Question 13

Yes
1
Very High
Studies have shown viable seed set, but plants must be in the presence of other plants (outcross) to set seed.
Beever, Ross E., and Stephanie L. Parkes. 1996. “Self-Incompatibility in Cordyline Australis (Asteliaceae)”. New Zealand Journal of Botany 34: 135\textendash137. doi:10.1080/0028825X.1996.10412701.

14. Question 14

Yes
1
Medium
An investigation into the species demonstrated self-incompatibility (another plant is necessary for pollination/seed set). Wild trees in the area demonstrated: the total number of fruits summed for 3 ultimate infructescence branches per tree averaged 148-160 fruits. Each fruit had 1-16 seeds, with means of 2.5-4.2 per fruit. This means between 370-672 seeds per 3 panicles on average, assuming outcrossing. (Beever & Parkes 1996)
Jepson has an unabridged note on the species indicating that the population in Sonoma, California had not yet been observed to have flowered. (Jepson)
The plant seems to have 3- many stems that contain infloresences in photographs. (USDA Plants: photos)
Beever, Ross E., and Stephanie L. Parkes. 1996. “Self-Incompatibility in Cordyline Australis (Asteliaceae)”. New Zealand Journal of Botany 34: 135\textendash137. doi:10.1080/0028825X.1996.10412701.
“USDA-NRCS Plants Database”. 2014. http://plants.usda.gov/java/nameSearch.

15. Question 15

Yes
1
High
"Mean germination of samples of 10 seeds from each of the nine inter-plant crosses was 6.2." (Beever & Parkes 1996)
Beever, Ross E., and Stephanie L. Parkes. 1996. “Self-Incompatibility in Cordyline Australis (Asteliaceae)”. New Zealand Journal of Botany 34: 135\textendash137. doi:10.1080/0028825X.1996.10412701.

16. Question 16

No
0
High
A sample of 28 wild populations in the native range showed age at first flowering between 6-10 years typically.
Harris, Warwick, Ross E. Beever, Stephanie Parkes, Bruce Smallfield, Ruth-Anne Anderson, and Sue Scheele. 2006. “Genotypic Variation of the Flowering Phenology of Cordyline Australis (Laxmanniaceae) Grown at Three Locations in New Zealand”. New Zealand Journal of Botany 44: 23\textendash39. doi:10.1080/0028825X.2006.9513003.

17. Question 17

No
0
Medium
Calflora lists the flowering period at 3 months, which is consistent with other sources. (Calflora)
Calflora. 2016. “Calflora California Wild Plant Database”. Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/.

18. Question 18

Yes
1
High
The plant is known to be eaten and spread by birds. (Kaka 2013; Thorsen et al. 2009)
K\=ak\=a, Alfie. 2013. “Ti Kouka: A Feast for Birds Big and Small” 2020. Karori Sanctuary Trust. https://www.visitzealandia.com/Whats-On/ArtMID/1150/ArticleID/44/Ti-kou….
Thorsen, Michael J., Katharine J. M. Dickinson, and Philip J. Seddon. 2009. “Seed Dispersal Systems in the New Zealand Flora”. Perspectives in Plant Ecology, Evolution and Systematics 11: 285\textendash309. doi:10.1016/j.ppees.2009.06.001.

19. Question 19

No
0
Medium
Described as being dispersed by birds and animals. The seed is heavy, with no specialized mechanism for wind or water dispersal.
Thorsen, Michael J., Katharine J. M. Dickinson, and Philip J. Seddon. 2009. “Seed Dispersal Systems in the New Zealand Flora”. Perspectives in Plant Ecology, Evolution and Systematics 11: 285\textendash309. doi:10.1016/j.ppees.2009.06.001.

20. Question 20

No
0
Medium
The seeds are within fruits and they have no specialized mechanism of attachment.
Thorsen, Michael J., Katharine J. M. Dickinson, and Philip J. Seddon. 2009. “Seed Dispersal Systems in the New Zealand Flora”. Perspectives in Plant Ecology, Evolution and Systematics 11: 285\textendash309. doi:10.1016/j.ppees.2009.06.001.

Evaluation Notes

New climate match map linked and attached 10/31/202205 (not proofed for accuracy with climate match questions answered previously). - JBurger

Total PRE Score

7
20
64

PRE Score Legend

The PRE Score is calculated by adding the point totals for each (answered) question.

< 13 : Low Potential Risk
13 - 15 : Moderate Potential Risk
> 15 : High Potential Risk

Questions Answered Legend

It is important to answer at least 16 questions to consider a PRE Score as "valid".

≥ 16 : Valid (80% or more questions answered)
≤ 15 : Invalid (not enough questions answered)

Evaluation Credits and Citation


Screener:  Lynn Sweet

 

Below is a recommend citation when referencing this evaluation in other works:

Sweet, Lynn. "Cordyline australis -- California" Plant Risk Evaluator (PRE) published 2020-02-11 https://pretool.org/evaluations/1726

 


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Evaluation Reviewers

Jutta Burger reviewed on 2025-11-01

 

Associated Project

There are no associated projects.


 

Associated Organizations, Agencies, and Institutions

PlantRight
California Invasive Plant Council (Cal-IPC)

 

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