Family

Fabaceae

Distribution

Most material assigned to this entity occurs in the region from Paynes Find and Yalgoo N to the Barlee Range and the southern Pilbara region in the vicinity of Newman, however, there are records further E from near Leonora, Cundeelee (c. 200 km E of Kalgoorlie) and McKay Range (Little Sandy Desert). Not unexpectedly this distribution encompasses the geographic range of both A. fuscaneura and A. pteraneura.

Description

Shrub or tree 3–7 m tall. Branchlets obscurely ribbed or ribless, the ribs not resinous or (at extremities of branchlets) with a veneer of translucent resin. New shoots dark-coloured, with glandular hairlets ±persistent on expanding phyllodes. Phyllodes 50–100 (–120) mm long, 0.8–1.5 mm wide, incurved to sigmoid or sinuous, rarely straight or with a few recurved, flat to terete, never all terete as in A. pteraneura, when flat (as in A. fuscaneura) then intermixed with a few (normally the youngest ones) that are compressed to terete, mostly dull green. Gland normally 2–9 mm above the pulvinus, lamina often slightly kinked or swollen at the gland. Pods commonly dark brown and sometimes tinged purplish, normally winged (wing commonly rather narrow, c. 1 mm wide), rarely bevel-edged.

Specimens

W.A.: Cundeelee, P. Boswell E1 (PERTH: flowering specimen, need pods to confirm identification); 63 km S of Meekatharra on Great Northern Highway to Cue, B.R. Maslin 9041 (PERTH); Watertharra Creek, 23.5 km W of Mount Magnet on road to Yalgoo, B.R. Maslin & J.E. Reid BRM 9790 (PERTH); Paynes Find – Thundelarra road, c. 10 km NW of Great Northern Highway, c. 15 km due N of Paynes Find, B.R. Maslin & J.E. Reid BRM 9964B (PERTH); c. 1.3 km W of Great Northern Highway, Fortescue River floodplain area, 3 km NW of Capricorn roadhouse, 10 km due SE of Newman, J.E. Reid 8 (PERTH); South Barlee Range, 7 Sept. 1959, A. Robison s.n. (PERTH 00490954).

Notes

The occasional specimens with phyllodes exceeding 10 cm long are difficult to distinguish from the more widespread A. paraneura. However, in plants of A. fuscaneura – pteraneura group the branchlets and phyllodes are never pendulous and the youngest 1–3 phyllodes on the new shoots are covered by dark-coloured glandular hairlets that completely obscure the underlying nerves and conventional white hairs. In A. paraneura the youngest 1–3 phyllodes are commonly finely or sometimes obviously striate with at least some white appressed hairs visible between the nerves that are normally invested with glandular hairlets; only occasionally are the nerves and hairs obscured as in A. fuscaneura – pteraneura group.

As discussed by B.R.Maslin & J.E.Reid, Nuytsia 22: 213 (2012) there are a number of specimens that appear to be intermediates or intergrades between A. fuscaneura and A. pteraneura; these specimens are labeled ‘A. fuscaneura-pteraneura group’. Because of the complex patterns of variation involved specimens assigned to Acacia fuscaneura - pteraneura group often cannot be easily discriminated from A. fuscaneura or A. pteraneura. Further field and herbarium study, and especially genetic information, is needed to resolve these complexities. Note: Recent study has shown that two of the specimens referred by Maslin & Reid (l.c.) to A. fuscaneura-pteraneura group are better placed elsewhere, namely, B.R. Maslin 8994 is now regarded as A. ? pteraneura and B.R. Maslin & J.E. Reid BRM 9964B is A. fuscaneura.

FOA Reference

Flora of Australia Project

Author

B.R.Maslin