Acacia hamiltoniana Maiden, J. & Proc. Roy. Soc. New South Wales 53: 199 (1920)
Hamilton’s Wattle
Bushy shrub normally to 3 m high. Branchlets finely ribbed, dark red, glabrous. Phyllodes mostly ascending to erect, often patent at ends of branchlets, variable, linear to linear-oblanceolate or narrowly elliptic, 3–6 (- 8) cm long, usually 2.5–5 mm wide, narrowed at base, glaucous to subglaucous, glabrous, 1-nerved; lateral nerves absent; gland not prominent, 0–7 mm above pulvinus. Inflorescences racemose; raceme axes 0.5–4 cm long, glabrous; peduncles 2.5–3.5 mm long, glabrous; heads globular, subdensely 9–15-flowered, golden; bracteole laminae transversely elliptic, dark brown, white-fimbriolate. Flowers 5-merous; sepals united; petals 1-nerved. Pods to 5.5 cm long, 1 cm wide, firmly chartaceous to thinly coriaceous, black, glabrous. Seeds oblique, end ones sometimes longitudinal, oblong to elliptic to ovate, 4–5 mm long, somewhat shiny, black; aril clavate.
Occurs in the Great Divide and its foothills from near Rylstone S to the Clyde R. near Nerriga, N.S.W. Grows in sand or sandy loam on sandstone outcrops in Eucalyptus forest or woodland and heath.
The nomenclature of A. hamiltoniana is linked to that of A. adunca and is discussed by L.Pedley, Austrobaileya 1: 286–287 (1980) and B.R.Maslin, Telopea 6: 43–47 (1994).
Some specimens from Mt Wilson in the Blue Mtns (e.g. R.Coveny 2902 , CANB, NSW, PERTH) are atypical in having phyllodes which are very narrow (1.5–2 mm wide) and/or acuminate (normally obtuse-mucronulate to acute).
Related to A. obtusata which is distinguished especially by its wider phyllodes (5–16 mm), gland generally farther above the pulvinus (5–40 mm), 15–27-flowered heads and longitudinal seeds. The flower-heads of these two species have a distinctive facies, i.e. the 1-nerved petals of adjacent flowers overtop the dark brown bracteoles and are not contiguous when in bud; A. hakeoides and A. williamsonii are similar but are distinguished by their narrower pods and glands further above the pulvinus.
Habit may resemble that of A. decora , a species possessing a distinctive, often golden pubescence on its peduncles and raceme axes.
Type of accepted name
Leura, N.S.W. Dec. 1907, A.A.Hamilton ; syn: NSW; Leura, N.S.W., Sept. 1908, A.A.Hamilton ; syn: NSW; isosyn: BM n.v ., fide L.Pedley, Austrobaileya 1: 286 (1980), PERTH; Leura, N.S.W., Dec. 1910, A.A.Hamilton ; syn: NSW; isosyn: AD, B, E, K, MEL, MO, NY, PERTH, TL, US, Z; Leura, N.S.W., 2 Oct. 1911, A.A.Hamilton ; ?syn: NSW, as ‘J.G.Hamilton’; isosyn: PERTH; Leura, N.S.W., Sept. 1912, A.A.Hamilton ; ?syn: K, MEL–?specimens seen by Maiden.
Synonymy
Acacia sieberiana Tausch, Flora 19: 420 (1836), non DC. (1825) nec G.H.A . Scheele (1843), nom. nud . [I.F.Tausch provided a new name for ‘A. crassiuscula Sieb.’, represented by Sieber 464 , but did not provide a description.]
Acacia obtusata var. hamiltonii Maiden (as ‘Hamiltoni’), Forest Fl. New South Wales 5: 153; pl. 181 (1912). Type: Leura, N.S.W., Dec. 1907, A.A.Hamilton ; syn: NSW; Leura, N.S.W., Sept. 1908, A.A.Hamilton ; syn: NSW; isosyn: BM n.v. , fide L.Pedley, Austrobaileya 1: 286 (1980), PERTH; Fl. Novae Hollandia [N.S.W.], F.Sieber 464 ; syn: NSW; isosyn: FI, G, G-DC, K, P.
[ Acacia linearifolia A.Cunn., non A.Cunn. ex Maiden & Blakely: in sched., as to Blue Mtns, Oct. 1825, A.Cunningham 84 (BM, K both n.v ., fide L.Pedley, Austrobaileya loc. cit. ; see B.R.Maslin, Telopea 6: 43- 47 (1994), for discussion]
[ Acacia crassiuscula auct. non H.L.Wendl.: e.g. G.Bentham, Fl. Austral. 2: 372 (1864) p.p. , as to F.Sieber 464 ]
Illustrations
J.H.Maiden, loc. cit . (1912), as A. obtusa var. hamiltonii ; T.Tame, Acacias SE Australia 157, fig. 173, pl. 173 (1992).
Representative collections
N.S.W.: 2 km ESE of Sassafras on Nowra- Nerriga road, B.G.Briggs 3004 & D.Blaxell (NSW); Currant Mtn Gap, 24 km by road E of Rylstone, R.Coveny 6618 & P.Hind (NSW, PERTH); Bell (Mt Wilson road), 28 Sept. 1912, A.A.Hamilton (NSW); Du Faurs Rocks, Mt Wilson, B.R.Maslin 5887 (MEL, MEXU, NSW, PERTH).
(BRM)
The information presented here originally appeared on the WATTLE CD-ROM which was jointly published by the Australian Biological Resources Study, Canberra, and the Department of Parks and Wildlife, Perth; it was produced by CSIRO Publishing from where it is available for purchase. The WATTLE custodians are thanked for allowing us to post this information here.
