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PRE — Plant Risk Evaluator

Acacia saligna -- California

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Evaluation Summary


photo by floydwafer

Evaluation Date:  2020-01-12

Screener:  Lynn Sweet
 
Plant:  Acacia saligna
Common Name(s):
Golden wreath wattle, Orange wattle, Port Jackson wattle

State:  California

PRE Score:  17
Questions Answered:  19
Screener Confidence (%):  69

Executive Summary

This is a shrubby tree native to Australia. It has been noted as invasive in areas with a similar climate to the study area, California. It is known to outcompete native species, spread vegetatively and produce an abundance of seed, though there was not a good source of information about seed dispersal. The species is fairly well documented and there was adequate information available based on its history of invading native vegetation in South Africa.

Climate Matching Map

https://weedmap.cal-ipc.org/climatematch/?areaType=states&areaList%5B0%5D=06&ma…
Attachment Size
climatematch-acacia_saligna-california-20251024.pdf (1.15 MB) 1.15 MB

1. Question 1

Yes
1
Very High
Naturalized where it is not native in Africa, Australia and the United States (USDA GRIN).
“Taxonomy - GRIN-Global Web V 1.9.8.2”. 1729. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=613.

2. Question 2

Yes
2
Very High
Naturalized where it is not native in Africa, Australia and the United States (USDA GRIN).
Naturalized in Southeastern Australia, South Africa, southern Europe, and the west coast of the United States in similar climates (GBIF).
Naturalized in the southwestern Cape Province, South Africa (Milton & Hall 1981).
The species occurs in 7 counties in coastal and southern California, the region of interest. (Calflora)
Milton, S. J., and A. V. Hall. 1981. “REPRODUCTIVE BIOLOGY OF AUSTRALIAN ACACIAS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA”. Transactions of the Royal Society of South Africa 44: 465-87. doi:10.1080/00359198109520589.
“Taxonomy - GRIN-Global Web V 1.9.8.2”. 1729. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=613.
Secretariat, GBIF. 2016. “GBIF Backbone Taxonomy”. Copenhagen, Denmark: GBIF Secretariat. https://www.gbif.org/.
Calflora. 2016. “Calflora California Wild Plant Database”. Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/.

3. Question 3

Yes
2
Very High
The species is invasive in Cyprus, Israel and South Africa. (GISD)
The species has been noted to be invasive in the southwestern Cape of South Africa. (Holmes et al. 1987)
No references cited.

4. Question 4

Yes
3
Very High
The species is invasive in Cyprus, Israel and South Africa, all of which are a similar climate to the study area, California, USA. (GISD)
The species has been noted to be invasive in the southwestern Cape of South Africa, which is similar in climate. (Holmes et al. 1987; Holmes & Cowling 1997)
Holmes, P. M., I. A. W. MacDonald, and J. Juritz. 1987. “Effects of Clearing Treatment on Seed Banks of the Alien Invasive Shrubs Acacia Saligna and Acacia Cyclops in the Southern and South-Western Cape, South Africa”. Journal of Applied Ecology 24: 1045\textendash1051. doi:10.2307/2404000.
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 317\textendash332. doi:10.2307/2404879.
Nature, International Union for the Conservation of. 2006. “Global Invasive Species Database”. http://www.issg.org/.

5. Question 5

Yes
1
Very High
Acacia paradoxica is on the California noxious weed list (CDFA). 3 other Acacias are on the California Invasive Plant Council Inventory as of this writing (January 2020) (Cal-IPC, 2020)
“California Invasive Plant Inventory”. 1729. California Invasive Plant Council, Berkeley, CA. https://www.cal-ipc.org/plants/inventory/.
2018. “CDFA’s Division of Plant Health’s Pest Ratings and Proposals”. http://blogs.cdfa.ca.gov/Section3162/?page_id=170.

6. Question 6

Yes
2
High
Yes, the balance of occurrences are in areas matching the climate in the study region.
The following areas match the climate of the region of concern: west coast of the US (7 counties in California, USA), central Mexico; southern Europe and the Mediterranean; very northern Africa (Mediterranean); the middle East (Israel, Palestine); South Africa (Cape and eastern region); Western Australia and southeastern Australia. (GBIF)
The following areas where the plant occurs do not match the climate of the study region:
Pakistan, Ethiopia, Sweden, the North Island of New Zealand, and the occurrences in South America. (GBIF)
Secretariat, GBIF. 2016. “GBIF Backbone Taxonomy”. Copenhagen, Denmark: GBIF Secretariat. https://www.gbif.org/.

7. Question 7

Yes
1
Medium
Noted to produce "dense shade" in long-invaded areas in South Africa.
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 317\textendash332. doi:10.2307/2404879.

8. Question 8

Yes
1
Medium
After fire a "dense sward of Acacia seedlings is usually the result," outcompeting the native fynbos species after fire. The species may also resprout after fire.
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 317\textendash332. doi:10.2307/2404879.

9. Question 9

No
0
Medium
Not listed as a health risk to humans or animals. (Canada BIF, FDA)
Examined as feed for goats, found to be not a candidate as a whole food source. (Degen et al. 1997)
Canada, Government of. 2019. “Canadian Poisonous Plant Information System”. http://www.cbif.gc.ca/eng/species-bank/canadian-poisonous-plants-inform….
“FDA Poisonous Plant Database”. 2015. US Food and Drug Administration, Washington, DC. http://www.accessdata.fda.gov/scripts/plantox/index.cfm.
Degen, A. A., A. Blanke, K. Becker, M. Kam, R. W. Benjamin, and H. P. S. Makkar. 1997. “The Nutritive Value of Acacia Saligna and Acacia Salicina for Goats and Sheep”. Animal Science 64: 253\textendash259. doi:10.1017/S1357729800015812.

10. Question 10

Yes
1
Medium
Areas in the Cape Peninsula in South Africa were noted to have >80% canopy cover of the species (notably high for a Mediterranean ecosystem).
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 317\textendash332. doi:10.2307/2404879.

11. Question 11

Yes
1
High
Noted to spread by both "root suckers and seed." (Flora of Australia) Can resprout from underground tissue post-fire. (Holmes & Cowling, 1997)
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 15. doi:10.2307/2404879.

12. Question 12

No
0
Very Low
The species occurs on upland sites and the species wasn't noted to spread beyond immediately from the vegetative reproduction. (Holmes & Cowling 1997)
Holmes, P. M., and R. M. Cowling. 1997. “The Effects of Invasion by Acacia Saligna on the Guild Structure and Regeneration Capabilities of South African Fynbos Shrublands”. Journal of Applied Ecology 34: 15. doi:10.2307/2404879.

13. Question 13

Yes
1
Very High
Noted to reproduce by seed.
2019. “Flora of Australia - Online”. Canberra. http://www.ausflora.org.au.

14. Question 14

Yes
1
High
Seeds falling within seed traps below the canopy were noted to catch 5,443 seeds per meter square per year.
Milton, S. J., and A. V. Hall. 1981. “REPRODUCTIVE BIOLOGY OF AUSTRALIAN ACACIAS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA”. Transactions of the Royal Society of South Africa 44: 465-87. doi:10.1080/00359198109520589.

15. Question 15

No
0
Medium
Germination without treatment is shown to be limited.
Milton, S. J., and A. V. Hall. 1981. “REPRODUCTIVE BIOLOGY OF AUSTRALIAN ACACIAS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA”. Transactions of the Royal Society of South Africa 44: 465-87. doi:10.1080/00359198109520589.

16. Question 16

Very Low
I could not locate this information.
No references cited.

17. Question 17

No
0
Medium
Flowers "July-November" in Australia (Flora of Australia online)
Flowers March, April, May (3 months) in California (Calflora)
"Pod and seed fall: The pods and seeds of Acacia longifolia and A. saligna fall over a six week period, three to four months after the fall of withered flowers." This observation from South Africa. (Milton & Moll 2008)
2019. “Flora of Australia - Online”. Canberra. http://www.ausflora.org.au.
Calflora. 2016. “Calflora California Wild Plant Database”. Berkeley, California: The Calflora Database [a non-profit organization]. http://www.calflora.org/.
Milton, Suzanne J., and EUGENE J. MOLL. 2008. “Phenology of Australian Acacias in the S.W. Cape, South Africa, and Its Implications for Management”. Botanical Journal of the Linnean Society 84: 295\textendash327. doi:10.1111/j.1095-8339.1982.tb00367.x.

18. Question 18

No
0
Low
Even though it was noted in a species summary in GISD as being dispersed by birds, the original reference cited shows only: water, mammals and ants as dispersal agents (Appendix 6). (Henderson 1998). No distance or other information was found, and no specific adaptations for long-distance dispersal were noted.
"The seeds of these species have small grey-white funicles (Fig. 16), unlikely to attract frugivorous dispersers, and are not presented to potential dispersers while on the tree, the pods being both deciduous and dehiscent." (Milton & Moll 2008)
Nature, International Union for the Conservation of. 2006. “Global Invasive Species Database”. http://www.issg.org/.
Henderson, L. 1998. “Invasive Alien Woody Plants of the Southern and Southwestern Cape Region, South Africa”. Bothalia 28 (21).
Milton, Suzanne J., and EUGENE J. MOLL. 2008. “Phenology of Australian Acacias in the S.W. Cape, South Africa, and Its Implications for Management”. Botanical Journal of the Linnean Society 84: 295\textendash327. doi:10.1111/j.1095-8339.1982.tb00367.x.

19. Question 19

No
0
Low
There are no specific adaptations to disperse via these methods. See image, GRIN.
Literature indicates that this species does occur on some water courses and may have spread downstream to other locations but this seems not special to this species in any way.
Milton, S. J., and A. V. Hall. 1981. “REPRODUCTIVE BIOLOGY OF AUSTRALIAN ACACIAS IN THE SOUTH-WESTERN CAPE PROVINCE, SOUTH AFRICA”. Transactions of the Royal Society of South Africa 44: 465-87. doi:10.1080/00359198109520589.
System, USDA ARS National Plant Germplasm. 2019. “Germplasm Resources Information Network (GRIN Taxonomy) Acacia Saligna”. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomydetail?id=981.

20. Question 20

No
0
Medium
No specific adaptations for this. This species is not in wildflower packets. It is used for stock fodder and grown in plantations in many areas. I did not find any specific information about mode of spread from the intentional introductions.
Database, Global Invasive Species. 2017. “GISD Website”. https://www.gbif.org/species/search?dataset_key=b351a324-77c4-41c9-a909….

Evaluation Notes

Climate match map and link added + some edits made to references 10/24/2025 (J. Burger)

Total PRE Score

17
19
69

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. "Acacia saligna -- California" Plant Risk Evaluator (PRE) published 2020-01-12 https://pretool.org/evaluations/1722

 


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Evaluation Reviewers

Jutta Burger reviewed on 2025-10-24

 

Associated Project

There are no associated projects.


 

Associated Organizations, Agencies, and Institutions

PlantRight
California Invasive Plant Council (Cal-IPC)

 

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