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Clump formation. Photographer: B.R. Maslin
Photographer: B.R. Maslin
, Hedland, photo G.F. Craig, ADJUSTED.jpg)
Photographer: G.F. Craig
Photographer: C. Harwood
Photographer: J. Maslin
, BRM 7305.jpg)
Photographer: B.R. Maslin
, c 20 km S Nullagine, BRM 17 July 2000.jpg)
Photographer: B.R. Maslin
, Leaf veins, cd 005-35.jpg)
Photographer: B.R. Maslin
Photographer: B.R. Maslin
Photographer: M.W. McDonald
Photographer: J. Maslin
Photographer: B.R. Maslin
, LSWE 7061, lab photo by Fiona McCallum.jpg)
Seed from one herbarium voucher. Scale in mm. Photographer: F. McCallum.
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Photographer: O. Strewe
Botanical name
Acacia colei Maslin & L.A.J. Thomson var. colei, Austral. Syst. Bot. 5: 737, figs 1 & 5 (1992)
Common name
Cole's Wattle
Aboriginal name
Gurganyan and Gargardu (Yindjibarndi), Gurlganyan (Ngarluma) and Karranyongu (Kurrama)
Description
Typically large, spreading, well-formed shrubs 2-4 m high with many ascending, straight, slender main branches from near ground level, on the most fertile sites it may develop into small, single-boled trees to 7 (-9) m high, the crowns spreading (to 4 m across) and somewhat open, plants dense and rounded in some regrowth situations. Bark grey and smooth on main trunks but reddish brown towards the ends of the branches. Branchlets acutely angular and brown at extremities, soon terete, densely sericeous with minute, closely appressed, straight, silvery hairs. New shoots pale yellow sericeous and often tinged brown by resin hairs when first initiated, hairs soon aging silvery. Phyllodes normally obliquely narrowly elliptic, narrowed at both ends, (7-) 9-23 (-25) cm long, (1.5-) 2-5 (-5.5) cm wide, ascending to erect, sometimes inclined to patent with age, ±straight but normally shallowly recurved at apices, sericeous hairs as on branchlets (indumentum especially evident on young phyllodes and becoming sparser with age), silvery green, silvery grey-green or silvery blue; with 3 (-4) main longitudinal nerves (nerves becoming obscure towards phyllode apex and some are confluent and ±contiguous with the lower margin at base), the minor nerves numerous and anastomosing to form a longitudinally-orientated reticulum; the apex terminated by a knob-like hard point 0.5-1 mm. Gland absent from apex of phyllode. Inflorescences rudimentary 2-headed racemes with axes to 0.5 mm long; peduncles 3-6 mm long, sometimes to 9 mm when in fruit, appressed-hairy, the indumentum sometimes sparse; spikes large and showy, 3-7 (-8) cm long, bright golden, the flowers close together in the bud but becoming sub-densely arranged at anthesis. Flowers 5-merous; calyx very shortly dissected; petals hairy. Pods linear, raised over the seeds and moderately constricted between them, 2-4 (-5) mm wide, thinly coriaceous-crustaceous, openly and strongly curved (sometimes into an open circle), dehisced valves somewhat twisted, entangled and often persisting on the plants as conspicuous, ±spherical clumps (resembling birds' nests from a distance), reddish brown. Seeds longitudinal in the pods, obloid or sometimes obloid-ellipsoid or obloid-ovoid, 3.5-4 mm long, glossy, very dark brown to black; aril bright yellow.
Characteristic features
Shrubs or sometimes small trees. Branchlets acutely angular and brown at extremities, densely sericeous. New shoots pale yellow sericeous aging silvery sericeous. Phyllodes large (mostly 9-23 cm x 2-5 cm), mostly ascending to erect, ±straight but normally shallowly recurved at apices, with a distinct silvery sheen (overall crown colour is silvery green, silvery grey-green or silvery blue) due to sericeous indumentum (which is especially evident on young phyllodes, the hairs becoming sparser with age), with normally 3 main longitudinal nerves (some confluent and ±contiguous with the lower margin at base of phyllode), the minor nerves numerous and anastomosing to form a longitudinally-orientated reticulum; apical point knob-like, no gland at apex of phyllode. Spikes large (mostly 3-7 cm long) on short peduncles (mostly 3-6 mm); petals hairy. Pods openly and strongly curved (sometimes into an open circle), ±glabrous, dehisced valves somewhat twisted, entangled and often persisting on the plants as conspicuous, ±spherical clumps. Seeds very dark brown to black, the aril bright yellow.
Distribution and ecology
Widespread in northern Australia between latitudes 16 degrees and 22 degrees S where it extends from the Pilbara and southern Kimberley regions in Western Australia, eastwards through the Great Sandy and Tanami Deserts to Northern Territory and to the Gulf country and Simpson Desert in western Queensland. In the Pilbara var. colei is common but it has a scattered distribution, mostly in areas north of the Fortescue River where it frequently forms dense, nearly pure stands, especially in water-gaining sites. It also grows on Dolphin Island in the Dampier Archipelago and is known from one population on Barrow Island. Acacia colei is a colonising species and may form dense regrowth populations in disturbed sites such as road verges, gravel pits and burnt areas. It grows in a variety of soils including red-brown stony clay, deep aeolian sand, red sandy loam and fine-textured clay and silty clay. These soils are typically neutral but range from acidic (pH 5.5) to alkaline (pH 8.5). Some populations occur on the margins of saline drainage systems, e.g. Lake Gregory and Eighty-Mile Beach in Western Australia. Further ecological information is provided by Doran and Turnbull (1997).
Flowering and fruiting period
Flowering has been recorded from May to September but the peak flush is June July. Pods with mature seeds have been collected mostly from September to November; however, seed is sometimes present in other months. The seeds ripen synchronously and fall from the plants within 1-2 weeks under hot, windy weather conditions.
Taxonomy
Two varieties are recognized within A. colei, var. colei and var. ileocarpa, but in the absence of pods it is difficult distinguishing them (see var. ileocarpa for discussion). Both varieties occur in the Pilbara but with var. colei being the more common by far.
Affinities
Acacia colei is a hexaploid species which appears to have evolved as an allopolyploid from A. neurocarpa (diploid) and A. cowleana (tetraploid), see Moran et al. (1992). The species was originally confounded with A. holosericea and is sometimes confused with A. cowleana or A. elachantha. These species all possess relatively large phyllodes, spicate inflorescences, thin-textured pods and black, glossy seeds with a bright yellow aril; except for A. neurocarpa all the above-mentioned species occur in the Pilbara. Acacia cowleana and A. elachantha are mostly distinguished from A. colei (both varieties) by their phyllodes which are generally more wide-spreading and are shallowly to strongly recurved over their entire length, have more widely-spaced main longitudinal nerves with fewer anastomosing minor nerves between them, also the main nerves are normally not confluent with the lower margin at the base of the phyllode; these two species also have glabrous petals and generally straight pods. Putative hybrids between A. colei var. colei and A. elachantha occur in Northern Territory (see McDonald and Maslin 1997). Although the phyllodes of A. colei often superficially resemble those of A. holosericea they are shallowly recurved towards their eglandulose apices (phyllodes straight and with a gland at the base of the apical mucro in A. holosericea) and have a more elongated reticulum (see Maslin and Thomson 1992 for more details). Variety colei (but not var. ileocarpa) is further distinguished from A. holosericea by its curved (not coiled) pods.
Notes
Variety colei is fast growing, short lived (about 6-10 years), has variable coppicing ability and regenerates from seed following fire.
It has ornamental potential in the Pilbara region on account of its attractive growth form and silvery foliage.
The seeds of var. colei were an important food source of central Australian Aborigines (Latz 1995); they are highly nutritious containing 21% protein, 10% fat and 57% carbohydrate (Maggiore and Latz, pers. comm.). Although potentially toxic non-protein amino acids are found in seeds of A. colei they occur at levels well below those that would cause problems; the subject of toxicity of Acacia seeds is briefly reviewed by Maslin et al. (1998).
As reported by Juluwarlu Aboriginal Corporation (2003) indigenous peoples of the central and western Pilbara used seed of A. colei for food (eaten whole, either raw or cooked). The seeds were also ground with a barruu (grinding stone), mixed with water and cooked in hot ashes to make a mardimirri (damper). An edible gum is also obtained from the branches. Indigenous peoples in the Kimberley region use A. colei for a range of purposes: stems for making spears, sticky unripe pods moistened to produce a lather for cleaning purposes, green seed roasted in the pods and ripe seed ground to a flour for making damper or for a baby food paste (Kenneally et al. 1996).
Both varieties of A. colei have been planted in tropical dry-zones of West Africa (e.g. Senegal and Niger) where they have been used for amenity purposes (windbreak and ornamental), fuelwood production (the wood is hard with a high density of about 870 kg/m3 and a calorific value of 4670 kcal/kg) and for environmental rehabilitation (soil improvement and erosion control). Recently the seeds of A. colei (which are produced in large quantity from an early age) have been used as an alternative source of human food in these regions, but var. ileocarpa is preferred to var. colei for this purpose (see var. ileocarpa for details).
Further information on the use of A. colei is given in Thomson (1989), Maslin and Thomson (1992), Doran and Turnbull (1997) and McDonald and Maslin (1997).
Conservation status
Not considered rare or endangered.
Origin of name
This species is named after the noted CSIRO seed collector Mr E.G. (Jerry) Cole who assisted in extensive botanical and seed collections of the species in 1984.
References
Doran, J.C. and Turnbull, J.W. (1997). Australian trees and shrubs: species for land rehabilitation and farm planting in the tropics. ACIAR Monograph No. 24. pp. 384. (Australian Centre for International Agricultural Research: Canberra.)
Juluwarlu Aboriginal Corporation (2003). Wanggalili: Yindjibarndi and Ngarluma Plants. pp. 128. (Juluwarlu Aboriginal Corporation: Roebourne, Western Australia.)
Kenneally, K.F., Edinger, D.C. and Willing, T. (1996). Broome and beyond: Plants and people of the Dampier Peninsula, Kimberley, Western Australia. pp. 256. (Department of Conservation and Land Management: Western Australia.)
Latz, P.K. (1995). Bushfires and Bushtucker: Aboriginal plant use central Australia. pp. 400. (IAD Press: Alice Springs.)
Maslin, B.R. and Thomson, L.A.J. (1992). Re-appraisal of the taxonomy of Acacia holosericea A. Cunn. ex Don, including the description of a new species, A. colei, and the reinstatement of A. neurocarpa A. Cunn. ex Hook. Australian Systematic Botany 5: 729-743.
Maslin, B.R., Thomson, L.A.J., McDonald, M.W. and Hamilton-Brown, S. (1998). Edible Wattle Seeds of Southern Australia: A review of species for use in semi-arid regions. pp. 108. (CSIRO Publishing: Collingwood, Victoria.)
McDonald, M.W. and Maslin, B.R. (1997). Acacia colei var. ileocarpa (Leguminosae: Mimosoideae), a new taxon from the tropical dry-zone of north-west Australia. Nuytsia 11(2): 219-223.
Moran, G.F., Thomson, L., Grant, J. and Bell, C. (1992). Distribution of genetic variation within two dry-zone Acacia species and implications for their genetic improvement. pp. 74-81. In: A.P.N. House and C. Harwood (eds) Australian Dry-zone Acacias for Human Food. Proceedings of a workshop held at Glen Helen, Northern Territory, Australia, 7-10 August, 1991. pp. 151. (Australian Tree Seed Centre, CSIRO Division of Forestry: Canberra.)
Thomson, L.A.J. (1989). Report to AIDAB on "Seeds of Australian Trees". Advisory visit to Kenya and West Africa Nigeria, Niger, Burkina Faso and Senegal 27 March - 6 May 1989. (Australian Tree Seed Centre, CSIRO Forestry and Forest Products: Canberra.)