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Natural populations

As currently recognised this species extends along the Western Slopes of the Great Dividing Range from the Gilgandra district in New South Wales, to western Victoria. In South Australia it extends west to the southern Flinders Ranges and Kangaroo Island [1]. This species varies from being a low straggly shrub to an erect shrub up to 2 m tall. There are at least three variants of A. acinacea [1,2]. The typical variant, from the Bendigo area in Victoria, is a tetraploid. Two other more widespread variants that differ in habit (erect versus pendulous) are diploids. This species grows on a range of sites which are mainly sandy in the east of its range but extend to clayey and calcareous sites in South Australia [3,4].

Flowering and seeds

This species flowers during May to September in South Australia [4] and August to October in Victoria and New South Wales [3]. Mature pods are present during summer [5].There are about 50 viable seeds per gram [5]. Nicking or boiling the seeds in water for a minute at 100°C is required to induce germination. The seeds start to germinate in about 17 days if grown at 25°C (but this response is only based on one seedlot) [5].

Cultivation and uses

Acacia acinacea is a fast growing, frost and drought tolerant, nitrogen-fixing shrub. It is in demand in revegetation programs in some parts of it range for its ability to pioneer degraded sites and is highly recommended as an ornamental [4]. Caution has been advised when sourcing seed from this species as at least three genetic races have been identified [2] and its morphological variation is likely to have a taxonomic basis [see 1].

Key descriptors:
Climate parameters
Annual rainfall 400-700 mm
Rainfall distribution pattern uniform or winter
Mean annual temperature 8-23 °C
Mean max. temperature of the hottest month 24-31 °C
Mean min. temperature of the coldest month 0-5 °C
Frosts: up to 20 or greater than 20 per year
Frost intensity: light to moderate (0 to -5°C) or heavy (greater than -5°C)
Altitude: 90-650 metres
Tolerance of climate extremes
Drought: known to be moderately drought tolerant or known to be tolerant of protracted droughts
Fire: killed by damaging fire
Frost: tolerates frosts in the 0° to -5°C range or tolerates heavy frosts colder than -5°C
Soil factors
Texture: clay loam, light to medium clay (35-50% clay), loam, sandy loam, sandy clay loam or sand
Soil pH reaction: acidic (less than 6.5), neutral (6.5-7.5) or alkaline (greater than 7.5)
Soil depth: skeletal to shallow (less than 30 cm) or moderate to deep (30-100 cm or greater)
Drainage: well-drained
Salinity: non-saline
Tolerance of adverse soils
Extremes in pH: acidity
Extremes in texture: sand
Salinity: nil - sensitive to saline soils
Soil waterlogging tolerance: nil - sensitive to waterlogged soils
Biological traits under cultivation
Habit: evergreen, shrub less than 2 m tall, multi-stemmed from or near ground level or shrub or small tree less than 5 m tall
Longevity: moderate to long lived (>15 years) or short-lived less than 15 years
Growth rate: fast
Erosion control potential: excellent for sandy sites
Root system: shallow and spreading, fixes nitrogen via root symbiot, forms root suckers
Shade tolerance: grows best in full sunlight
Wood density: low (less than 600 kg/cubic metre) or mod. to high (greater than 600 kg/cubic metre)
Carbon sequestration potential: low
Uses
Potential farm use: good ornamental attributes
Specialty products: pollen has value in apiculture
Urban use: good as an ornamental or amenity plant
Potentially undesirable attributes
Growth habit: mod. to strong propensity to root sucker or shallow roots may outcompete adjacent plants
Weediness: high potential based on its biology

References

[1] Maslin BR (2001) Acacia acinacea. Flora of Australia, 11A: 587-588.

[2] Broadhurst LM, Young AG, Thrall PH, Murray BG (2006) Sourcing Seed for Acacia acinacea, a Key Revegetation Species in South Eastern Australia. Conservation Genetics 7: 49-63.

[3] Cunningham GM, Mulham WE, Milthorpe PL, Leigh JH (1992) Plants of Western New South Wales, Inkata Press, Port Melbourne, Victoria.

[4] Whibley DJE, Symon DE (1992) Acacias of South Australia (South Australian Govt Printer, Adelaide).

[5] Gunn BV (2001) Australian Tree Seed Centre Operations Manual. Internal Publication, CSIRO Australian Tree Seed Centre, ACT. [Online at http://www.ensisjv.com/Portals/0/atsc-opmanualcomplete.pdf  Accessed March 2008]

Internet links

Charles Sturt University's Virtual Herbarium:  http://www.csu.edu.au/herbarium/acacacin.html

eFloraSA Electronic Flora of South Australia: http://www.flora.sa.gov.au/cgi-bin/texhtml.cgi?form=speciesfacts&family=&genus=Acacia&species=acinacea&iname=&submit=Search 

PlantNET National Herbarium of New South Wales: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acacia~acinacea

World Wide Wattle: http://www.worldwidewattle.com/speciesgallery/acinacea.php

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