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Botanical name

Common name

Description

Characteristic features

Distribution and ecology

Flowering and fruiting period

Variation

Affinities

Notes

Conservation status

Origin of name

References

Acacia stenophylla

Botanical name

Acacia stenophylla Cunn. ex Benth., London J. Bot. 1: 366 (1842)

Common name

River Cooba (Standard Trade Name and preferred common name), River Myall, Eumong, and many more (see Cunningham et al. 1981)

Description

Somewhat bushy, multi-stemmed shrubs or trees mostly 4-6 m tall (Pilbara plants), can reach up to 20 m on very favourable sites elsewhere, single-stemmed or divided into several stems about 1 m or more above the ground, the trunks straight and 12-15 cm in diameter at breast height (Pilbara plants), freely root-suckering (although this was not apparent in the Mulga Downs population). Bark grey, thin and finely longitudinally fissured (but with a tendency to break with a rectangular fracture at about breast height) on main trunks, smooth and dull pale green on upper branches. Branchlets light orange or dull yellow, glabrous to sericeous, not or scarcely pendulous. New shoots with bright green and shiny (not viscid). Phyllodes linear, strap-like and rather lax, 15-40 cm long, 2-7 mm wide, coriaceous, ascending to erect but some pendulous, glabrous or sparsely appressed-hairy, dull green to slightly sub-glaucous; parallel longitudinal nerves numerous, fine and with a discrete but narrow space between them (nerves not as close together as in A. coriacea); narrowed at apex into acute or acuminate, often curved, non-spiny points. Inflorescences short racemes normally 3-5 mm long; peduncles 6-13 mm long, appressed-hairy or rarely glabrous; heads globular, creamy white to pale yellow, (20-) 25-40-flowered. Flowers 5-merous; sepals -united. Pods moniliform, indehiscent, breaking readily at constrictions between the seeds, 10-26 cm long, (6-) 8-12 mm wide, woody, obscurely longitudinally wrinkled, glabrous, pale lime green just prior to maturity. Seeds longitudinal in the pods, broadly ellipsoid to obloid-ellipsoid, 7-9 mm long, dark brown; funicle scarcely arillate.

Characteristic features

Shrubs or trees. Phyllodes very long and narrow (15-40 cm x 2-7 mm), linear, strap-like and rather lax, some pendulous, glabrous or sparsely appressed-hairy, with numerous, parallel longitudinal nerves (with a discrete but narrow space between each nerve). Inflorescences short racemes (normally 3-5 mm long); heads globular, creamy white to pale yellow. Pods moniliform, indehiscent, breaking readily at constrictions between the seeds, woody, large (10-26 cm long, mostly 8-12 mm wide). Seeds large (7-9 mm long), funicle scarcely arillate.

Distribution and ecology

Very widely distributed in inland arid areas of Australia where it ranges from the far eastern Kimberley region of Western Australia (with a disjunct occurrence in the Pilbara), eastwards through Northern Territory to Queensland (west of the Great Divide) and south to the Murray-Lachlan-Darling River system in New South Wales, Victoria and South Australia. Acacia stenophylla is rare in the Pilbara where it is known from just two populations on Mulga Downs Station, on the floodplain of the Fortescue River. It usually grows in heavy soils along watercourses subject to periodic flooding where it frequently forms single-species stands. Comprehensive summaries of its habitat characteristics are given in Turnbull (1986), Doran and Turnbull (1997) and CAB International (2000); see also Pedley (1978), Cunningham et al. (1981) and Whibley and Symon (1992). The Mulga Downs populations grow in hard, red-brown heavy clay along a diffuse watercourse.

Flowering and fruiting period

There are very few Pilbara collections of this species which makes it difficult to accurately assess its phenology within the region. Nevertheless, flowering specimens have been collected in May and pods with mature seed in September and October. Over its extensive geographic range this species is mostly reported to flower irregularly throughout the year, or from March to July, and to produce mature pods from September to about December (Queensland, see Pedley 1978) or February to May (South Australia, see Bonney 1994). Acacia stenophylla is capable of producing very large seed crops (Turnbull 1986) but because pods are indehiscent or tardily dehiscent this is one of the most difficult Acacia species from which to collect seeds. Parrots and galahs are known to eat seeds out of pods (Bonney 1994).

Variation

There is variation in stem and growth form across the extensive range of this species. The above description applies only to plants found in the Pilbara region.

Affinities

The long phyllodes and growth form may resemble A. coriacea subsp. pendens, however, it is unknown if the two are closely related. Subspecies pendens is most readily distinguished from A. stenophylla by its striate, leathery pods which do not break at the constrictions, its conspicuous, orange seed aril, shorter racemes and its phyllodes with finer nerves that are closer together (lacking discrete inter-nerve spaces as in A. stenophylla). Acacia pachycarpa is similar to A. stenophylla in having a sometimes weeping growth habit, long, strap-like phyllodes, pale-coloured flowers and woody pods, it also grows near water courses. However, A. pachycarpa is readily distinguished from A. stenophylla by its simple, spicate inflorescences, non-moniliform pods and obscurely reticulately nerved phyllodes. The large moniliform pods of A. stenophylla may be mistaken for those of A. sclerosperma subsp. sclerosperma, however, the two taxa are not at all closely related; subsp. sclerosperma is readily recognized by its smaller stature, narrower phyllodes with fewer longitudinal nerve, seeds with small but red terminal arils and flower-heads a bright golden colour.

Notes

Acacia stenophylla is a hardy, long-lived species with a moderate to fast growth rate, it coppices and has a vigorous root suckering habit. It is moderately drought and frost tolerant, highly salt-tolerant and is tolerant of alkalinity and periodic flooding. It is considered a woody weed in parts of the Channel country in northwestern Queensland.

Useful for soil stabilization, where its suckering propensity is an advantage.

The wood is very hard, heavy, close-grained, dark coloured, beautifully marked and takes a fine polish, it planes excellently and shows a very smooth surface; the basic density is 690-750 kg/m3 and the air-dry density is 900 kg/m3. The wood produces an excellent fuel and its timber is suitable for furniture and fence posts.

Acacia stenophylla is not highly prized as a stock fodder although in Queensland it is eaten fairly readily but not cut to any extent for drought feed (Everist 1969).

This attractive willow-like tree has potential for planting in inland areas as an ornamental, and because of its bushy crowns, for shade and as a windbreak.

This species is regarded by Maslin and McDonald (2004) as having only moderate prospects as a crop plant for high volume wood production within the agricultural regions of southern Australia.

Seeds and pods were roasted and used by Australian Aboriginal people as a food source, however, it is not one of the species recommended by Maslin et al. (1998) for widescale planting as source of human food.

Much of the above information is taken from the summaries provided by Turnbull (1986), Marcar et al. (1995), Doran and Turnbull (1997), CAB International (2000) and Maslin and McDonald (2004). These publications provide additional source references as well as further information on the ecology, cultivation and utilisation of this species.

Conservation status

Although this species is very uncommon in the Pilbara it has a very wide distribution within Australia and is therefore not considered rare or endangered.

Origin of name

The botanical name is derived from the Greek stenos (narrow) and phyllon (leaf) in reference to the (long) narrow phyllodes that characterize this species.

References

Bonney, N. (1994). What seed is that? A field guide to identification, collection and germination of native seed in South Australia. pp. 324. (Neville Bonney: Adelaide.)

CAB International (2000). Forestry Compendium Global Module. CD ROM. (CAB International: Wallingford, UK.)

Cunningham, G.M., Mulham, W.E., Miltnorpe, P.L. and Leigh, J.H. (1981). Plants of western New South Wales. pp. 766. (Government Printing Office: Sydney.)

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.)

Everist, S.L. (1969). Use of fodder trees and shrubs. Advisory leaflet No. 1024. pp. 44. (Queensland Department of Primary Industries, Division of Plant Industry: Brisbane.)

Marcar, N.E., Crawford, D.F., Leppert, P., Jovanovic, T., Floyd, R. and Farrow, R. (1995). Trees for Saltland: a guide to selecting native species for Australia. pp. 72. (CSIRO, Division of Forestry: Australia.)

Maslin, B.R. and McDonald, M.W. (2004). AcaciaSearch: Evaluation of Acacia as a woody crop option for southern Australia. RIRDC Publication No. 03/017. pp. 267. (Rural Industries Research and Development Corporation: Canberra.)

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.)

Pedley, L. (1978). A revision of Acacia Mill. in Queensland. Part 1. Austrobaileya 1(2): 75-234.

Turnbull, J.W. (ed.) (1986). Multipurpose Australian trees and shrubs: lesser-known species for fuelwood and agroforestry. pp. 316. (Australian Centre for International Agricultural Research: Canberra.)

Whibley, D.J.E. and Symon, D.E. (1992). Acacias of South Australia. Handbook of the flora and fauna of South Australia Series. pp. 328. (South Australian Government Printer: Adelaide.)