Acacia colei Maslin & L.A.J.Thomson, Austral. Syst. Bot. 5: 737; 733, fig. 1 & 739, fig. 5 (1992)
Spreading shrub 2–4 m high, occasionally tree to 9 m high. New shoots sericeous, the hairs pale yellow-brown soon ageing silvery. Branchlets acutely angled, silvery-sericeous. Phyllodes normally obliquely narrowly elliptic, ±straight but commonly shallowly recurved at apices, normally 11–20 cm long, 1–4.5 (5.5) cm wide, with knob-like mucro, silvery green or silvery grey-green, sericeous, the 3 or 4 main nerves per face confluent and ±contiguous with the lower margin at base, with minor nerves forming an obvious longitudinally orientated reticulum. Inflorescences rudimentary 2-headed racemes with axes to 0.5 mm long; peduncles 4–6 mm long, appressed-puberulous to sericeous, with indumentum sometimes sparse; spikes 3–6.5 cm long, golden. Flowers 5-merous; sepals united; petals hairy. Legumes openly and strongly curved (var. colei ) or tightly and irregularly coiled or twisted (var. ileocarpa ), dehisced valves somewhat twisted, entangled and persisting as conspicuous clumps following dehiscence, 3.5–4 mm wide, thinly coriaceous-crustaceous, glabrous or subglabrous. Seeds longitudinal, normally oblong, 4–4.5 mm long, glossy, very dark brown to black; aril bright yellow.
Widespread in northern Australia between latitudes 16o and 22° S where it extends from the Pilbara and southern Kimberley region, W.A., E across the Great Sandy and Tanami Deserts, N.T., to the Gulf country and Simpson Desert in western Qld.
Acacia colei is a hexaploid and appears to have evolved as an allopolyploid from A. neurocarpa (diploid) and A. cowleana (tetraploid), fide G.F.Moran e t al. , in A.House & C.Harwood (eds), Austral. Dry-Zone Acacias Human Food (1992). As discussed by B.R.Maslin & L.A.J.Thomson, loc. cit. , these species are most readily distinguished by their degree of pod coiling and by the shape, width and venation of their phyllodes. Acacia colei and A. cowleana are frequently sympatric and occasionally hybridise (e.g. near Elliot, N.T., L.Thomson LXT1226 , PERTH). Acacia colei and A. neurocarpa are infrequently sympatric (e.g. Dampier Penin. and near Halls Creeek, W.A., Fish R. Gorge, N.T.). Acacia colei is also related to A. thomsonii and it sometimes hybridizes with the typical variant of A. elachantha .
The phyllodes of A. colei often superficially resemble those of A. holosericea but A. colei can be distinguished by its phyllodes which are shallowly recurved towards their eglandulose apices (straight and with a gland at the base of the apical mucro in A. holosericea ) and which have a more elongated reticulum, see B.R.Maslin & L.A.J.Thomson, loc. cit. , for more details. Variety colei is further distinguished from A. holosericea by its curved (not coiled) pods.
Both varieties of A. colei have shown potential for multipurpose use in tropical dry-zones of West Africa. In Senegal and Niger they have been grown as a source of fuelwood and for environmental rehabilitation and recently their seeds have have been used as an alternative source of human food in these regions, see references in B.R.Maslin & L.A.J.Thomson, loc. cit. and M.W.McDonald and B.R.Maslin, Nuytsia 11: 223 (1997) for further information.
Two varieties are recognized.
Pods tightly and irregularly coiled or twisted
Acacia colei Maslin & L.A.J.Thomson var. colei
Terminal branchlets brown. Phyllodes 20–45 (–55) mm wide. Pods curved, sometimes into an open circle. Seeds 3.5–4 mm long.
Extending from the Pilbara and southern Kimberley region, W.A., E across the Great Sandy and Tanami Deserts, N.T., to north-western Qld. Grows in a variety of soil types; frequently forms dense, nearly monotypic stands along dry, stony or sandy drainage lines. It is a colonising species and a component of many semi-arid, subtropical plant communities, especially the Acacia -dominated scrubs and tall open shrublands of north-western Australia. Dense regrowth populations often develop in disturbed sites such as road verges, gravel pits and burnt areas.
Type of accepted name
Broome townsite, W.A., 23 Oct. 1991, T.Willing 47 ; holo: PERTH; iso: BRI, CANB, K, MEL, NSW.
[ Acacia holosericea auct. non A.Cunn. ex Don: L.Pedley, Proc. Roy. Soc. Queensland 74: 57 (1964) p.p. , as to R.A.Perry & M.Lazarides 2667 and M.Lazarides 6525 ; B.R.Maslin, in J.P.Jessop (ed.), Fl. Central Australia 142 (1981)]
B.R.Maslin & L.A.J.Thomson, loc. cit. ; J.C.Doran & J.W.Turnbull (eds), Australian Trees & Shrubs: species for land rehabilitation & farm planting in the tropics 129 (1997).
W.A.: near Cape Borda, Dampier Penin., B.R.Maslin 4933 (BRI, PERTH); beside track to Gregory Gorge, 11 km from Millstream pipeline road, C.Olsson 24 (PERTH); 23.5 km E of Halls Creek on Duncan Hwy, L.Thomson LXT85 (PERTH). N.T.: 9 km N of Elliot on Stuart Hwy, L.Thomson LXT37 (PERTH); 5.3 km E of Hooker Creek (on road to Duck Ponds Waterhole), L.Thomson LXT56 (PERTH). Qld: 38.8 km N of Dugald R., T.K.Vercoe 187 (PERTH)
Acacia colei var. ileocarpa M.W.McDonald & Maslin, Nuytsia 11(2): 219, figs 1 & 2 (1997)
Curly-podded Cole’s Wattle
Terminal branchlets often orange. Phyllodes 10–25 (–40) mm wide. Pods tightly and irregularly coiled or twisted. Seeds 3–3.5 (–4) mm long.
Scattered in the southern Kimberley region of W.A. where it extends from near Derby eastward to the western extremity of N.T. at the Negri River; also occurs in the Fortescue River drainage system in the Pilbara region of W.A. In the southern Kimberley var. ileocarpa grows in open woodlands near floodplains and drainage lines, on clay loams (pH 5.5–6.5) derived from alluvia or limestone. In the Pilbara it occurs on slightly alkaline sandy loam (pH 7.5–8.5), mostly in tall open Acacia shrubland. Flowers June–July.
Plants of var. ileocarpa display a range of variation in phyllode size and shape similar to or perhaps even greater than var. colei . Its phyllodes are commonly 10–25 mm wide and as such tend to be slightly narrower (and often more attenuate) than those of var. colei. However , plants with wider than normal phyllodes (to 40 mm across and clearly within the range of variation for var. colei ) occur scattered throughout the geographic range of the taxon. Kimberley plants of var. ileocarpa have seeds 3–3.5 mm long and this appears to be a slight, but consistent, difference from var. colei which occurs in the same area (seeds 3.5–4 mm long). In the Pilbara region, however, the seeds of var. ileocarpa tend to be slightly longer (to 4 mm).
Variety ileocarpa differs most significantly from var. colei in having tightly, irregularly coiled or twisted pods (these being very similar to those found on related species A. holosericea and A. neurocarpa ) and in the absence of fruits it is normally difficult to distinguish the two. The two varieties are normally allopatric but sympatry occurs, e.g. Luluigui Station (south-west of Fitzroy Crossing), south of the Negri River crossing on the Duncan Highway (south of Kununurra) and at Rockhole Creek (south of Halls Creek). Herbarium specimens suggest that sympatry may occur in some Pilbara populations but this needs to be confirmed by further field observations. No intergradation between the two varieties has been observed.
Type of accepted name
About 38 km E of Gibb River turnoff at Derby, on road to King Leopold Range, W.A., 13 Oct. 1992, B.R.Maslin 7219; holo: PERTH; iso: CANB, K.
M.W.McDonald and B.R.Maslin, loc. cit.
W.A.: between Rober [Robe River] and Millstream, H.Demarz 7663 (BRI, PERTH); Gibb River road, 68.2 km SE of Windjana Gorge turn off, C.E.Harwood & M. McDonald CEH 474 (PERTH); Great Northern Highway, 16 km SW of Halls Creek (c.1 km NE of turnoff to Carranya Station at Koongie park), B.R.Maslin 7155 (PERTH); c. 400 m S of the Negri River crossing, 136.6 km S along Duncan Highway (from turn off at Victoria Highway), M.McDonald 1931 (PERTH); 17 km E of Halls Creek on Duncan Highway, L.Thomson LXT1291-1295 (all PERTH). N.T.: 7 km SE of Negri River on Duncan Highway, SSE of Kununurra, B.R Maslin 7120A (PERTH); 23.6 km S of the Negri River crossing along the Duncan Highway, M.McDonald 1936 (PERTH).
The Fl. Australia treatment of A. colei has been modified here in WATTLE to incorporate var. ileocarpa .