Acacia angustissima (Miller) Kuntze, Rev. Gen. Pl. 3(2): 47 (1898)
Bushy shrub to 4 m tall. Branchlets glabrous or sparsely appressed pubescent, ribbed, soon becoming terete, the low ribs produced distally as brown lines separated by paler epidermal tissue. Stipules scarious, oblong. c. 3 x 1 mm, caducous. Leaves bipinnate, scattered on stem; leaf axis (including petiole) 4.5–13 cm long, sparsely appressed hairy; petiole 2–5.5 cm long; pinnae 3–9 pairs, axes 3.5–5.5 cm long; pinnules oblong, obtuse, discolorous, 18–24 pairs per pinna, the most proximal much reduced, 3.5–7 x 1.8–2.4 mm, glabrous or with a few appressed hairs beneath, secondary veins not apparent; foliar glands absent. Inflorescences simple in fascicles of 3–5 in the upper axils, or forming leafless terminal panicles; heads ovoid/obloid, white, with 15–30 pedicellate flowers (pedicles 0.6–1 mm long); peduncles 12–20 mm long, glabrous or sparsely appressed-pubescent. Flowers 5-merous, all parts glabrous; calyx sinuolately lobed 0.6–0.8 mm long; corolla deeply lobed, 2.5–3 mm long; stamens extremely numerous (100 or more), 5–5.5 mm long with minute anthers c. 0.1 mm long. Pods oblong, to 6 cm long, 1–1.5 cm wide, valves membranous, transversely veined, raised over seeds, glabrous, stipitate (stipe 5–8 mm long). Seeds transverse, depressed globular, dark brown, not shiny, c. 3.5 x 2.8 mm; funicle filiform, not thickened to an aril; pleurogram open;areole large, oblong (cf. Acacia subg. Acacia) paler than rest of surface with a pale halo outside the pleurogram.
Isolated naturalised populations of this New World species occur in central and northern Qld, especially around Ingham.
According to L.Pedley, Austrobaileya 1(4): 344–345 (1981) A. angustissima differs from all Acacia species found in Qld in having rather oblong heads of almost white flowers (with short pedicels) in paniculate inflorescences and bipinnate leaves without glands.
For more information on the Australia occurrence of this species see L.Pedley (loc. cit). See D.Isely, Sida 3: 368–373 (1969) for information regarding the U.S.A. occurrence of this species.
This species was not included in the Fl. Australia treatment of Acacia ; the above description, based on Qld plants, was provided for use in WATTLE by L.Pedley.