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Photographer: B.R. Maslin
, BRM 5255, ORIGINAL SCAN, ADJUSTED RICHARD WOODMAN.jpg)
Thick, corky bark. Photographer: B.R. Maslin
, BRM 5255, ORIGINAL SCAN, ADJUSTED RICHARD WOODMAN.jpg)
Photographer: B.R. Maslin
Photographer: B.R. Maslin
, photos ex Luke Sweedman, ORIGINAL SCAN, ADJUSTED RICHARD WOODMAN.jpg)
Photographer: L. Sweedman
, BRM 8647, lab photo by Fiona McCallum ADJUSTED.jpg)
Seed from one herbarium voucher. Scale in mm. Photographer: F. McCallum.
Botanical name
Acacia sericophylla F. Muell., J. Proc. Linn. Soc., Bot. 3: 122 (1859)
Common name
Desert Dogwood (preferred common name), Desert Oak and Cork-bark Wattle
Aboriginal name
Pirrkala (Nyangumarta)
Description
Small, ±gnarled trees or sub-trees 2.5-6 m tall, to 10 m in Queensland (Pedley 1978), with a single stem or few mains stems from ground level, regenerating from the base following fire. Bark thick and corky, deeply furrowed, dark grey to black externally (often scorched by fire) but yellow and spongy beneath. Branchlets not pendulous, brittle and breaking easily, silvery sericeous (hairs straight and closely appressed) at ends of branchlets, becoming glabrous with age. New shoots pale citron-sericeous. Phyllodes tending to clump at ends of branchlets, narrowly linear, long and often strap-like, flat or rarely ±terete, (12-) 15-30 (-35) cm long, 1-4 (-7) mm wide, coriaceous and normally somewhat rigid, spreading to erect (not pendulous except sometimes on regenerating foliage), straight to shallowly or moderately incurved or recurved, densely and minutely sericeous when young but sub-glabrous with age (hairs often difficult to see without magnification and could be interpreted as absent), silvery grey-green to ±glaucous or sometimes green; with many fine, parallel, indistinct longitudinal nerves of uniform prominence or the central one slightly more pronounced than the rest; apices innocuous. Gland not prominent, situated on upper margin of phyllode (0-) 2-8 (-10) mm above pulvinus. Inflorescences mostly simple and in pairs (sometimes with a new vegetative shoot developing within the axil of the peduncles) but sometimes interspersed with rudimentary racemes 0.5-4 (-10) mm long; peduncles (8-) 10-20 (-30) mm long, densely silvery sericeous in flower but indumentum sometimes sparser when in pod; heads not showy, somewhat obscured by phyllodes, delicately fragrant, globular, pale lemon yellow, densely 30-40-flowered. Flowers mostly 5-merous; calyx shortly dissected; petals sparsely to densely hairy. Pods pendulous, moniliform, 15-25 (-33) cm long, 5-10 mm wide, coriaceous to ±woody, straight to shallowly or strongly curved before dehiscence, sometimes twisted at the constrictions between the seeds (but twisting is not as common nor as pronounced as often occurs in A. coriacea, nor are the undehisced pods markedly coiled), striate, densely silvery sericeous but indumentum sparser and often confined to constrictions between the seed on oldest pods (hairs minute and difficult to see without magnification, could be interpreted as absent). Seeds longitudinal in the pods, obloid-ellipsoid to ellipsoid, 4.5-7 mm long, 2.5-5 mm wide, dull or slightly shiny, very dark brown to black; with a large yellow or orange aril at one end.
Characteristic features
Small, ±gnarled trees or sub- trees. Bark thick and corky, deeply furrowed, dark grey to black externally but yellow and spongy beneath. Branchlets not pendulous, silvery sericeous. New shoots pale citron-sericeous. Phyllodes narrowly linear, long and narrow (mostly 15-30 cm x 1-4 mm) and often strap-like, spreading to erect, flat to ±terete, tending to clump at ends of branchlets, densely sericeous when young but sub-glabrous with age, finely multi-nerved. Inflorescences mostly simple and in pairs, sometimes a few rudimentary racemes present; peduncles (8-) 10-20 (-30) mm long; heads not showy, pale lemon yellow, delicately fragrant. Pods long (mostly 15-25 cm) and moniliform, coriaceous to ±woody, pendulous, straight to shallowly or strongly curved before dehiscence, striate -nerved. Seeds partially enclosed by a conspicuous yellow or orange aril.
Distribution and ecology
Widespread across the northern central arid zone from Western Australia through Northern Territory and South Australia to Queensland and New South Wales. Acacia sericophylla is not overly common in the Pilbara where it has a scattered distribution, growing in red sand or sandy loam on spinifex plains.
Flowering and fruiting period
Pilbara plants flower mainly between May and July and pods with mature seed have been collected between October and December. Elsewhere over its extensive geographic range this species may have a different phenology, for example, Queensland plants flower from January to July and fruit from May to November.
Variation
Not especially variable within the Pilbara.
Taxonomy
Until recently this species was regarded as a subspecies of A. coriacea (see Cowan and Maslin 1993), but is now treated as a distinct species. Although these two species are sometimes difficult to separate from herbarium material they have very distinctive field facies. Acacia coriacea is most reliably distinguished from A. sericophylla by its thinner, fibrous (not thick and corky) bark, but there are other characters such as growth form, pod curvature, peduncle length and habitat preference that are useful in distinguishing them as shown in the following key.
Bark thick and corky, yellow and spongy internally; peduncles (8-) 10-20 (-30) mm long; pods (prior to dehiscence) straight to shallowly or strongly curved (not irregularly or markedly coiled); ±gnarled trees or sub-trees with non-pendulous branchlets. Spinifex sandplains; Australia-wide distribution.
A. sericophylla
Bark thin, fibrous and longitudinally fissured; peduncles 3-10 (-13) mm long; pods (prior to dehiscence) markedly and often irregularly curved, twisted and/or openly coiled, sometimes (in subsp. coriacea) openly curved and not twisted or coiled. Northwest W.A.; coastal dunes and inland watercourses.
A. coriacea
Affinities
Acacia sericophylla has affinities to A. sibilans (see that species for distinguishing features). Sterile plants of A. sericophylla can be confused with Hakea lorea subsp. lorea ('Cork Tree' which has thick corky bark) or Grevillea striata ('Beefwood'). These species can have a superficially similar growth form and long foliage, and all three occur in the Pilbara region. In the absence of flowers or fruits one way of distinguishing them is to carefully examine the base of the foliage (best done with a x 10 magnification lens). In A. sericophylla there is a band of yellow tissue called the pulvinus at the base of the phyllodes and a tiny gland is situated on upper margin of the usually vertically flattened phyllodes, normally 2-8 mm above pulvinus. The leaves of Grevillea striata and Hakea lorea and on the other hand lack both the pulvinus and gland; furthermore, in G. striata the leaves are horizontally flattened whereas in H. lorea they are terete (phyllodes rarely ±terete in A. sericophylla).
Notes
A drought-tolerant, long-lived species which is reported to have a slow or moderate growth rate. The thick bark and ability to coppice from the base (and to regenerate by root suckers) make this a very fire-tolerant species. Would be a useful ornamental for inland plantings on account of its unusual growth form.
As reported by Latz (1999) the seeds of this species are an important source of food for traditional Aborigines of Central Australia. The fully formed but green pods are collected and lightly roasted, usually on a burning spinifex tussock, producing a pleasant smoked flavour to the seed when eaten. Fully mature seeds are also collected; these are soaked and then mashed by hand with water to form a kind of milk which is drunk. The timber is favoured for boomerangs and spears, the twig ash is used with pituri and burnt bark for decoration.
Although the phyllodes and pods of this species are eaten by stock in Central Australia and Queensland, they are relatively unpalatable, of only moderate nutritional value and are eaten only after ground feed is not available (Chippendale and Jephcott 1963).
Conservation status
Not considered rare or endangered.
Origin of name
The botanical name is derived from the Greek words sericos (silken) and phyllon (leaf) in reference to the dense silky hairs which are found especially on the younger phyllodes.
References
Chippendale, G.M. and Jephcott, B.R. (1963). Topfeed. The fodder trees and shrubs of Central Australia. Extension Article No. 5. pp. 51. (Northern Territory Administration, Animal Industry Branch: Alice Springs.)
Cowan, R.S. and Maslin, B.R. (1993). Acacia miscellany 9. The taxonomic status of Acacia coriacea (Leguminosae: Mimosoideae: Section Plurinerves). Nuytsia 9(1): 83-90.
Latz, P.K. (1999). Pocket Bushtucker: a field guide to the plants of Central Australia and their traditional uses. pp. 215. (IAD Press: Alice Springs.)