Shrub or tree to 15 m high, erect. Bark fissured, grey. Branchlets angular toward apices, otherwise terete, light green to brown, reddish in juveniles, sometimes pruinose or scurfy. Mature phyllodes narrowly elliptic to very narrowly elliptic, flat, mostly falcate, 5–17 cm long, (4–) 7–22 mm wide, thinly coriaceous, mostly glabrous, with 2 or 3 conspicuous longitudinal veins and 2 or 3 semi-prominent veins separate to base; minor veins (3–) 4–10 (–12) per mm and nonanastomosing; gland 1, basal, to 3 mm above pulvinus; immature phyllodes (when present) elliptic (subsp. diphylla) to very narrowly elliptic (subsp. blakei), 5–9.5 cm long, 15–35 (–40) mm wide. Inflorescences racemose; raceme axes 1–12 (–20) mm long. Spikes 2–6 cm long, pale yellow to yellow. Flowers 5-merous; calyx 0.5–0.8 mm long, barely to shortly dissected into broad lobes, with silvery villous hairs, or 0.3–0.5 mm with red-brown papillae on lobes and sometimes pubescent on tube; corolla 1.3–1.8 mm long, dissected to ⅓–½ of their length, glabrous; ovary pubescent at apex and base, or glabrous to variably tomentose. Pods linear, scarcely moniliform, straight or slightly curved, 3–10 cm long, 2–4 mm wide, glabrous or scurfy. Seeds longitudinal, broadly elliptic, 3.2–5.2 mm long, black; areole not depressed, open.
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