Mimosa bush (Acacia farnesiana)

Present distribution

Scientific name:	Acacia farnesiana (L.) Willd.
Common name(s):	Mimosa bush

Map showing the present distribution of this weed.

Habitat:

Native range between Texas and Bolivia (Kull, Rangan 2008), including semi-arid vegetal community (Navar, Bryan 1990) and “relatively mesic ecosystems” (Polley et al 2002). In Australia it “grows in schlerophyll woodland, shrubland and grassland, on alluvial clay soils and sandy loams, on open plains and near watercourses” (Harden 2002) and is also found growing by railways (Benson, McDougall 1996). Mean annual rainfall of between 400 mm to 750 mm; lasting dry seasons 4 to 6 months; mean annual temperatures range from 15 to 28 C; wide variety of soils, from heavy clays to sands; altitude of 2000 m (Parrotta 1992). Weed of pastures (Parrotta 1992) and watercourses (ISSG 2006).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Forestry; horticulture perennial; pasture dryland; pasture irrigation

Broad vegetation types
Heathland; grassy/heathy dry forest; swampy scrub; lowland forest; forby forest; high altitude shrubland/woodland; granitic hillslopes; rocky outcrop shrubland; western plains woodland; basalt grassland; alluvial plains grassland; semi-arid woodland; alluvial plains woodland; ironbark/box; riverine woodland/forest; chenopod shrubland; chenopod mallee; hummock-grass mallee; lowan mallee; broombush whipstick

Colours indicate possibility of Acacia farnesiana infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

map showing the potential distribution of mimosa bush

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Shrub to 3 m high with spiny stems (Wrigley, Fagg 1996), grows near water courses (Harden 2002) and can form almost pure stands (Foroughbakhch 1992) and sometimes “impenetrable thickets… limiting access to water” (ISSG 2006) – major impediment to access waterways	h	m
2. Reduce tourism?	Spiny appendages (stipules, to 25 mm long) at the base of the leaflets (Richardson et al 2006) – may effect some recreational uses	mh	mh
3. Injurious to people?	Spiny appendages (stipules, to 25 mm long) at the base of the leaflets (Richardson et al 2006) – large spines	h	mh
4. Damage to cultural sites?	Shrub to 3 m high (Wrigley, Fagg 1996) and can form almost pure stands (Foroughbakhch 1992) – moderate visual effect	ml	m
Abiotic
5. Impact flow?	Although it grows near watercourses (Harden 2002), it does not appear to affect water flow	l	m
6. Impact water quality?	Grows near watercourses and in dense thickets (Harden 2002) up to 3 m high Shrub to 3 m high (Wrigley, Fagg 1996) – may have a minor effect on light levels	ml	m
7. Increase soil erosion?	“considered useful for soil stabilisation in degraded drylands” (Parrotta 1992) – is likely to decrease the probability of soil erosion	l	mh
8. Reduce biomass?	Potential invader of grasslands (Polley et al 2002) – likely to increase biomass	l	h
9. Change fire regime?	“Although the aerial portions may be killed by fire, this plant soon regenerates from basal shoots” (ISSG 2006). As A. farnesiana invades “pastures, fallow land and disturbed natural vegetation” (Foroughbakhch 1992) it is likely to greatly change the frequency and intensity of fire risk	h	m
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Semi-arid Woodland (V); CMA = Mallee; Bioregion = Murray Mallee; VH CLIMATE potential. A. farnesiana is a potential invader of grasslands (Polley et al 2002) and has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… Almost pure stands… developed in some areas” (Foroughbakhch 1992), indeed, it was found that biomass increased with increasing planting density (Goel, Behl 2004) Likely to form a monoculture within the shrub layer; displaces all spp. within a strata/layer	h	h
(b) medium value EVC	EVC = Grassy Riverine Forest (D); CMA = North Central; Bioregion = Murray Fans; VH CLIMATE potential. A. farnesiana is a potential invader of grasslands (Polley et al 2002) and has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… Almost pure stands… developed in some areas” (Foroughbakhch 1992), indeed, it was found that biomass increased with increasing planting density (Goel, Behl 2004) Likely to form a monoculture within the shrub layer; displaces all spp. within a strata/layer	h	h
(c) low value EVC	EVC = Sandstone Ridge Shrubland (LC); CMA = Mallee; Bioregion = Lowan Mallee; VH CLIMATE potential. A. farnesiana is a potential invader of grasslands (Polley et al 2002) and has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… Almost pure stands… developed in some areas” (Foroughbakhch 1992), indeed, it was found that biomass increased with increasing planting density (Goel, Behl 2004) Likely to form a monoculture within the shrub layer; displaces all spp. within a strata/layer	h	h
11. Impact on structure?	A. farnesiana is a potential invader of grasslands (Polley et al 2002) and has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… Almost pure stands… developed in some areas” (Foroughbakhch 1992), indeed, it was found that biomass increased with increasing planting density (Goel, Behl 2004) – major effects on all layers. Forms monoculture.	h	h
12. Effect on threatened flora?	It has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… [forms] almost pure stands” (Foroughbakhch 1992) – likely to effect threatened flora but this was not identified in the literature.	mh	l
Fauna
13. Effect on threatened fauna?	It has “aggressive pioneer characteristics in the invasion of pastures, fallow land and disturbed natural vegetation… [forms] almost pure stands” (Foroughbakhch 1992) – likely to effect habitat of threatened fauna was not identified in the literature.	mh	l
14. Effect on non-threatened fauna?	As it forms “impenetrable thickets” (ISSG 2006) it is likely to change habitat dramatically which may lead to the possible extinction of non-threatened fauna	h	m
15. Benefits fauna?	As it is a prickly shrub (Wrigley, Fagg 1996) it is likely to provide harbour for small birds, as well as provide nectar for nectar-feeders – provides an important alternative food source and harbour to desirable species	ml	m
16. Injurious to fauna?	The spiny appendages (stipules, to 25 mm long) at the base of the leaflets (Richardson et al 2006) – large spines likely to be dangerous to fauna	h	mh
Pest Animal
17. Food source to pests?	“The seed pods are nutritious and are readily eaten by ungulates” (ISSG 2006), e.g. wild horses, goats and pigs – supplies food for one or more minor pests spp.	ml	m
18. Provides harbour?	As it forms “impenetrable thickets” (ISSG 2006) it is likely to provide harbour and permanent warrens for foxes and rabbits throughout the year	h	m
Agriculture
19. Impact yield?	It is persistent “in heavily grazed, mechanically cut, and herbicide-treated pastures” (Parrotta 1992) and although in Australia “pastoralists have long tolerated it as drought forage” (Kull, Rangan 2008) it is digested poorly in sheep (Ramirez, Ledezma-Torres 1997) – may affect pasture quantity and therefore livestock access to feed – major impact on quantity of produce (5-20%)	mh	mh
20. Impact quality?	A known seed contaminant of hay from the top end in the Northern Territory (CLMA 2004) - this may lead to produce being rejected for sale or export	h	m
21. Affect land value?	“As it often forms thorny thickets along some watercourses in Australia…can also hinder access to water” (ISSG 2006) – may decrease land value > 10%	h	m
22. Change land use?	“As it often forms thorny thickets along some watercourses in Australia, it can be a considerable nuisance during mustering and can also hinder access to water” (ISSG 2006). “Due to its prolific seed production, palatability to livestock, and rapid germination on disturbed soils, aroma can rapidly colonise pastures, often forming dense stands” (Parrotta 1992) – the fact that it is so hard to control and affects access to water may result in downgrading of the priority land use	mh	m
23. Increase harvest costs?	“As it often forms thorny thickets along some watercourses in Australia, it can be a considerable nuisance during mustering and can also hinder access to water” (ISSG 2006) – more time and labour would be required to regain access to waterways and to muster livestock	h	m
24. Disease host/vector?	None mentioned in the literature	m	l

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	Although scarification and other pretreatments of seeds increase germination rates, “seeds may be sown without pretreatment… germination takes place in the rainy season, but many seeds remain dormant for a full year before germinating” (Parrotta 1992) – requires natural seasonal disturbances such as seasonal rainfall for germination	mh	mh
2. Establishment requirements?	“is intolerant of shade and requires free growing space” (Parrotta 1992) – requires more specific requirements to establish	ml	mh
3. How much disturbance is required?	“Grows in schlerophyll woodland, shrubland and grassland, on alluvial clay soils and sandy loams, on open plains and near watercourses” (Harden 2002) and is also found growing by railways (Benson, McDougall 1996). It invades “pastures, fallow land and disturbed natural vegetation” (Foroughbakhch 1992) – establishes in relatively intact or minor disturbed natural ecosystems	mh	mh
Growth/Competitive
4. Life form?	Leguminous (Cervantes et al 1996)	mh	h
5. Allelopathic properties?	“Extracts from… A. farnesiana… caused moderate but significant inhibition [of Lemna aequinoctialis] with the most inhibited growths … 32% (seed)” (Allan, Adkins 2005) – allelopathic properties seriously affecting some plants	mh	mh
6. Tolerates herb pressure?	Leaves consumed by goats and sheep, although digested poorly in sheep (Ramirez, Ledezma-Torres 1997). Also browsed by white-tailed deer (Ramirez et al 1997). However it is persistent “in heavily grazed, mechanically cut, and herbicide-treated pastures” (Parrotta 1992) – consumed but not preferred	mh	h
7. Normal growth rate?	“Increased constantly across each growing season so it ought to develop rapidly its photosynthetic surface” (Foroughbakhch 1992). “Under field conditions on semiarid sites, seedling heights after 1 year are typically 30 to 50 cm” however if irrigated under nursery conditions, plants can grow to 210 cm in the first year (Parrotta 1992) – rapid growth rate (under ideal conditions)	h	mh
8. Stress tolerance to frost, drought, w/logg, sal. etc?	“Drought hardy, fire resistant, and susceptible to frost… tolerates saline soils” (Parrotta 1992), however it shows high yields in an area where hail and frost occurs yearly (Foroughbakhch 1992) Grows in a site that is subject to water logging, however this ‘restricts the normal plant growth’ (Goel, Behl 2004)	h	h
Reproduction
9. Reproductive system	“Prolific seed producer” (ISSG 2006) and “reportedly can be propagated vegetatively by cuttings. Although no data are available on vegetative reproduction under field conditions, the persistence of aroma in heavily grazed, mechanically cut, and herbicide-treated pastures suggests that the species coppices well” (Parrotta 1992) – sexual and possibly vegetative	h	m
10. Number of propagules produced?	Pods can contain between 11 and 23 seeds (Parrotta 1992) – above 2000	h	m
11. Propagule longevity?	“seeds remain viable for 30 years or more when stored under dry conditions at ambient temperature” (Parrotta 1992)	h	m
12. Reproductive period?	“may form dense thickets and become weedy” (Harden 2002) and is a “spreading, thicket-forming shrub” (Richardson et al 2006) – species forms self-sustaining monocultures	h	m
13. Time to reproductive maturity?	“known to flower as early as the second year following germination, with pods produced as early as the third year” (Parrotta 1992)	ml	mh
Dispersal
14. Number of mechanisms?	“The leaves and pods are much eaten by stock, which probably aid in diffusion of the seeds” (Standley, Streyermark 1946). On a regional scale seeds are dispersed by ocean currents (on which the seed pods can float for up to 600 km), traders, planters and farmers and on a local scale planters, water, livestock and wind are responsible for dispersal (Kull, Rangan 2008)	h	h
15. How far do they disperse?	the seed pods can float on ocean currents for 600 km (Kull, Rangan 2008) – very likely that at least one propagule will disperse greater than one kilometre	h	h

References

Allan S, Adkins S (2005) Searching for a natural herbicide: the role of medicinal plants? Fourth World Congress on Allelopathy. Allelopathy. Available at http://www.regional.org.au/au/allelopathy/2005/2/7/2680_allans.htm (verified 4 August 2008)

Benson D, McDougall L (1996) Ecology of Sydney Plant Species. Part 4 Dicotyledon family Fabaceae. Cunninghamia: A Journal of Plant Ecology for Eastern Australia 4(4), 552- 752. Available at http://www.rbgsyd.nsw.gov.au/__data/assets/pdf_file/57849/Cun4Ben552.pdf (verified 30 July 2008)

Central Land Management Association (CLMA) (2004) Land Talk: Newsletter of the CLMA. Vol. 12, No. 1. Available at http://www.clma.com.au/Landtalk%20PDF%20for%20website/LandTalk%20February%2004.pdf (verified 18 August 2008)

Cervantes V, Carabias J, Vázquez-Yanes C(1996) Seed germination of woody legumes from deciduous tropical forest of southern Mexico. Forest Ecology and Management 82(1-3), 171-184

Foroughbakhch R (1992) Establishment and growth potential of fuelwood species in northeastern Mexico. Agroforestry systems 19, 95-108

Goel VL, Behl HM (2004) Productivity assessment of three leguminous species under high-density plantations on degraded soil sites. Biomass and Bioenergy 27, 403-409

Harden GJ ed (2002) Flora of NSW. Vol. 2. Revised edition. Royal Botanic Gardens Sydney.

Invasive Species Specialist Group (ISSG) (2006) Acacia farnesiana. Global Invasive Species Database, IUCN/SSC Invasive Species Specialist Group. Available at http://www.issg.org/database/species/ecology.asp?si=49&fr=1&sts=sss (verified 18 August 2008)

Kull CA, Rangan H (2008) Acacia exchanges: Wattles, thorn trees, and the study of plant movements. Geoforum, 39(3), 1258-1272

Navar J, Bryan R (1990) Interception loss and rainfall redistribution by three semi-arid growing shrubs in northeastern Mexico. Journal of Hydrology 115, 51-63

Parrotta JA (1992) Acacia farnesiana (L.) Willd. International Institute of Tropical Forestry, United States Forestry Service. Available at http://www.fs.fed.us/global/iitf/pubs/sm_iitf049%20%20(5).pdf (verified 6 August 2008)

Polley HW, Tischler CR, Johnson HB, Derner JD (2002) Growth rate and survivorship of drought: CO2 effects on the presumed tradeoff in seedlings of five woody legumes. Tree physiology 22(6), 383-391

Ramirez RG, Ledezma-Torres RA (1997) Forage utilisation from native shrubs Acacia rigidula and Acacia farnesiana by goats and sheep. Small Ruminent Research 25, 43-50

Ramirez RG, Quintanilla JB, Aranada J (1997) White-tailed deer food habits in northeastern Mexico. Small Ruminent Research 25, 141-146

Richardson FJ, Richardson RG, Shepherd RCH (2006) Weeds of the South-East; An identification guide for Australia. FJ Richardson and RG Richardson, Merideth, Vic.

Sahu NP, Achari B, Banerjee S (1998) 7,3’-DIHYDROXY-4’-METHOXYFLAVONE from seeds of Acacia farnesiana. Pytochemistry 49(5), 1425-1426

Standley PC, Steyermark, JA (1946) Flora of Guatemala (Fieldiana: Botany. Vol 24 Part V). Chicago Natural History Museum.

Tierney DA (2006) The effect of fire-related germination cues on the germination of a declining forest understorey species. Australian Journal of Botany 54, 297-303

Tomar OS, Minhas PS, Sharma VK, Singh YP, Gupta RK (2003) Performance of 31 tree species and soil conditions in a plantation established with saline irrigation. Forest Ecology and Management 177, 333-346

Wrigley J, Fagg M (1996) Commonly grown Acacia. Text derived from the Acacia sections of the 4th edition of Australian Native Plants, Reed Books Pty Ltd. Available at http://www.anbg.gov.au/acacia/species.html (verified 1 August 2008)

Global present distribution data references

Australian National Herbarium (ANH) (2008) Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, Available at http://www.anbg.gov.au/avh/ (verified 3/12/08).

Calflora: Information on California plants for education, research and conservation. [web application]. (2008) Berkeley, California: The Calflora Database [a non-profit organization]. Available at http://www.calflora.org/ (verified 3/12/08).

Department of Sustainability and Environment (DSE) (2006) Flora information system [CD-ROM], Biodiversity and Natural Resources Section, Viridans Pty Ltd, Bentleigh.

EIS: Environmental Information System (2006) Parks Victoria.

Global Biodiversity Information Facility (GBIF) (2008) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 3/12/08).

IPMS: Integrated Pest Management System (2006) Department of Primary Industries.

Missouri Botanical Gardens (MBG) (2008) w3TROPICOS, Missouri Botanical Gardens Database, Available at http://mobot.mobot.org/W3T/Search/vast.html (verified 3/12/08).

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