Common Name

Lemon-scented Wattle

Family

Fabaceae

Distribution

Occurs in arid northern Australia, predominantly in the Kimberley region of Western Australia and far northwest Queensland, but populations extend to the Northern Territory near the respective borders. In Western Australia it is recorded from Camballin Station (south of Derby, west Kimberley) and the Halls Creek–Margaret River area in the east Kimberley, in the Northern Territory from the Kirkimbie Station and Barkly Homestead areas as well as collection from east of Benmarra, and in Queensland mainly from the Mount Isa–Camooweal area. The Western Australian occurrences from between Port Hedland and Anna Plains referred to in M.D. Tindale et al., Acacia sp. E, Flora of Australia 11B: 228 (2001), are now regarded as A. hilliana × A. stellaticeps.

Description

Spreading, multi-stemmed, resinous, viscid, aromatic (citrus odour), glabrous shrub 0.5–2 m high and to 2 (–4) m across, much branched, flat-topped. Bark fissured, grey-brown. Branchlets terete, obscurely ribbed. Phyllodes single or rarely two clustered at nodes, narrowly oblong-elliptic to linear but often broadest above the middle, (1.5–) 2–4 (–5.5) cm long, (1.5–) 2–4 (–5) mm wide, l: w = 6–20 (–30), flat, mostly shallowly incurved but often a few straight or shallowly sigmoid, bright green to dull greyish or subglaucous, with numerous, obscure or slightly pronounced longitudinal nerves; apex coarsely to ±sharply pungent; glands obscure, 1–2 (–3), the lowermost 4–15 (–22) mm above pulvinus, occasionally absent. Inflorescences simple; peduncles (10–) 15–30 (–35) mm long; spikes 0.9–2.5 (–3) cm long, golden. Flowers 5 merous; calyx 0.5–1.2 mm long, dissected to ½–⅘. Pods erect, linear-oblanceolate, basally tapered, flat, straight-sided, 2.5–5 cm long, 3–5 (–5.5) mm wide, woody, obliquely nerved, opening elastically from apex with dehisced valves recurved; margin thick and pale-coloured. Seeds oblique and seated in pronounced depressions, obloid-ellipsoid, 3.2–5 mm long, brown or olive-brown, with often darker, open areole; funicle-aril narrowly conical.

Phenology

Flowers recorded May.–Oct.

Habitat

Grows in gravelly, red or brown, skeletal soils on quartzite or laterite, on ridges or plains in spinifex-shrubland or savannah eucalypt woodland.

Specimens

W.A.: 4 miles [6.4 km] E of Mary R. crossing on Great Northern Hwy, J.R.Maconochie 1144 (DNA, NSW); 21.5 km SW of Nicholson HS on rd to Halls Creek, B.R.Maslin 7135 (K, MEL, PERTH).

N.T.: Old Tanami mine site, D.Keith 136 & B.Pellow (MO, NSW, SYD).

Qld: 45 km SSW of Lorraine Stn HS, I.D.Fox IDF3201 & G.W.Wilson (BRI); 5 miles [8 km] ESE of Coolullah Stn, M.Lazarides 3988 (CANB, DNA, NSW, PERTH); 49 miles [78.4 km] E of Camooweal township, R.A.Perry 759 (CANB, NSW, PERTH).

Notes

This taxon was treated as Acacia sp. E by M.D. Tindale et al., Flora of Australia 11B: 228 (2001).

Acacia citriodora is most closely allied to A. hilliana, which is readily distinguished by its phyllodes that are normally terete to compressed, narrower (0.5–1 mm wide/diam.) and more elongate (l: w = (25–) 30–94). Furthermore, the phyllodes of A. hilliana are normally sparsely tuberculate (very rarely tuberculate in A. citriodora) and many specimens have some phyllodes clustered in groups of two or three at the nodes (single at nodes or rarely a few paired in A. citriodora). Differences between A. citriodora and A. lysiphloia and A. arida are discussed by P.G. Kodela & B.R. Maslin, Nuytsia 27: 99–102 (2016). Acacia hilliana × A. stellaticeps from near the Pilbara region, Western Australia, is superficially very similar to A. citriodora but seemingly is not the same biological entity.

FOA Reference

Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia

Author

P.G. Kodela & B.R. Maslin