Acacia wattsiana

Acacia wattsiana F.Muell. ex Benth., Fl. Austral. 2: 374 (1864)

Watt’s Wattle , Dog Wattle

Shrub or tree 1–4 m high, obconic with a spreading, rounded, bushy crown. Branchlets acutely angled at extremities, reddish brown, glabrous. Phyllodes mostly obovate to narrowly oblanceolate, 3–7 cm long, mostly 5–12 mm wide, narrowed at base, rounded-obtuse, thinly coriaceous, glaucous, light green when young, glabrous; midrib slightly excentric; lateral nerves obscure; gland not prominent, 5–16 mm above pulvinus. Inflorescences racemose; raceme axes 10–25 mm long, glabrous; peduncles 3–9 mm long, slender, glabrous; heads globular, subdensely 12–20-flowered, yellow; buds obtuse. Flowers 5-merous; sepals united almost to their apices. Pods linear to narrowly oblong, to 9 cm long, 6–8 mm wide, firmly chartaceous to thinly coriaceous, glabrous. Seeds longitudinal, oblong to elliptic, c. 4.5 mm long, slightly shiny, dark brown to black; funicle encircling seed in a double fold, brittle, dark reddish to black; aril clavate.

Occurs from near Melrose, in the southern Flinders Range, south to Clare and Tothill Ranges, Northern Lofty region, S.A. A variant occurs at Nectar Brook and Brachina Gorge (see below). Grows in calcareous clay in woodland, open forest or tussock grassland.

A member of the ‘ A. microbotrya group’ related to A. quornensis . Acacia deuteroneura (Qld) has similar phyllodes to those of A. wattsiana except that they are 2-nerved; it is further distinguished by its pruinose branchlets, transverse seeds and pods 12–13 mm wide. Closely resembling A. chalkeri (N.S.W.) which differs in mucronulate phyllodes and more densely flowered heads: the relationship between these two species should be reassessed.

Acacia wattsiana F.Muell. ex Benth. (Nectar Brook variant)

A variant of uncertain rank occurs in the Flinders Ra. near Nectar Brook, c. 30 km SE of Port Augusta and on hilltops S of Brachina Gorge. It differs most obviously from typical A. wattsiana in the following ways: grows to an erect spindly tree 4 m tall; phyllodes narrowly elliptic to oblanceolate or obovate, obtuse to subacute, 2.5–7 (–10) cm long, 6–22 mm wide, coriaceous; gland 0–18 mm above pulvinus; racemes 3–7.5 cm long, heads 20–40-flowered; pods with scattered appressed hairs; grows on rocky ridgetops of pound quartzite with Triodia spp. (e.g. The Guardians, Brachina Gorge, E.N.S.Jackson 165 and M.C.O'Leary 2676, both AD; Nectar Brook, T.Hall 262, AD; Winninowie Ra, A.G.Spooner 8950, AD.  This taxon appears to hybridize with A. calamifolia and these plants may superficially resemble A. euthycarpa  or A. rivalis .

Type of accepted name

Broughton [Broughton Lodge Stn], Rocky R., S.A., Oct. 1851, F.Mueller s.n. ; holo: K; iso: G (sphalm ‘1854’), MEL, NSW.

Illustrations

F. von Mueller, Iconogr. Austral. Acacia dec. 5 [pl. 2] (1887); L.F.Costermans, Native Trees & Shrubs SE Australia 316 (1981); M.Simmons, Acacias Australia 2: 165 (1988); D.J.E.Whibley & D.E.Symon, Acacias S. Australia 2nd edn, 149 (1992).

Representative collections

S.A.: World’s End Ck, R.Bates 3321 (AD); c. 10 km W of Gladstone, B.Copley 2905 & 2906 (both AD); 5 km W of Tandowie on road to Wirrabara State Forest, B.R.Maslin 5998 (AD, MEXU, 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.