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Acacia bivenosa

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Acacia bivenosa DC., Prodr . 2: 452 (1825

Two Nerved Wattle

Shrub normally 1–3 m high, usually dense and glabrous. Branchlets often slightly pruinose. Phyllodes usually oblong-elliptic to obovate, usually 2–5 cm long and 6–25 mm wide with l:w = 2–5, with incurved to straight mucro, thin to subfleshy, green or glaucous, usually 2-nerved per face; glands commonly 3, lowermost prominent and 2–12 mm above pulvinus, distal glands smaller with one commonly adjacent to mucro. Inflorescences 6–7-headed racemes, mostly growing out with subsequent inflorescences simple; raceme axes 2–4 cm long; peduncles (10–) 15–35 mm long; heads globular, subdense, normally 16–23-flowered, deep golden; buds bright green. Flowers 5-merous; sepals united into a truncate calyx. Pods erect, submoniliform but constrictions not pronounced, to 8 cm long, 5–9 mm wide, firmly crustaceous, light brown. Seeds longitudinal, oblong-elliptic, 4–6 mm long, glossy, dark brown; aril red or orange.

Widespread in the Arid Zone of W.A., N.T. and western Qld, N of 25S, with an outlier on Dorre Is., Shark Bay, W.A. Grows in a variety of soils, including coastal sand, and on rocky hillsides and gullies, in shrubland, open shrubland and open woodland, often associated with spinifex.

A.R.Chapman & B.R.Maslin, Nuytsia 8: 249- 283 (1992), define and discuss the informal ‘A. bivenosa group’ which comprises the following 12 species, A. ampliceps , A. bivenosa , A. cupularis , A. didyma , A. ligulata , A. rostellifera , A. salicina , A. sclerosperma , A. startii , A. telmica , A. tysonii and A. xanthina . As discussed by A.R.Chapman and B.R.Maslin, loc. cit., A. bivenosa is a variable species. The phyllodes are often distinctly 2-nerved, but on plants with very narrow phyllodes and on many plants from N.T. and Qld, the second nerve can be reduced and obscure or even absent. In north-western W.A. a number of variants are recognised: plants from the Hamersley Ra. and on islands of the Dampier Archipelago have generally narrower than normal (5–12 mm wide, l:w = 3–8), narrowly elliptic to oblanceolate phyllodes (e.g. between Tom Price and the Wittenoom-Nanutarra road, B.R.Maslin 4667, PERTH); plants from Airlie Is. have atypically long (normally 5–9 cm), 1- or 2-nerved phyllodes (e.g. V.Long 165 , PERTH); at Dampier and in the Tom Price- Newman area a variant with a distinctive weeping habit is common (e.g. Burrup Penin., N of Dampier, B.R. Maslin 4740 , BRI, PERTH). The sympatric occurrence of plants with green phyllodes and those with glaucous phyllodes is not unusual and has no taxonomic significance. Occasional plants from N.T. and Qld have puberulous branchlets and raceme axes.

G. Bentham’s concept of A. bivenosa included A. xanthina ( Drummond 1: 283, Preiss 928 ) and A. didyma (Dirk Hartog Is., Cunningham [330] ), fide A.R.Chapman & B.R.Maslin, loc. cit . However, A. bivenosa is readily distinguished from these two more southerly distributed species by the more elongate phyllodes of A. xanthina and wider pods of A. didyma . Often sympatric with A. startii . Closely related to and sometimes difficult to distinguish from A. ligulata (possibly due to hybridisation), particularly in south-central N.T. where they are partially sympatric. In north-western W.A. it hybridises with A. ampliceps and probably also A. sclerosperma subsp. sclerosperma .

Type of accepted name

Western Australia [sphalm. ‘in Nouvelle Hollande, cote orient.’], ex herb. P, 1821; holo: G-DC; iso: BM, P.

Synonymy

Acacia binervosa DC, Mm. Lsgum. pt 8, 448 (1827), nom. illeg., presumably an orthographic variant for A. bivenosa DC. (1825).

Acacia elliptica A.Cunn. ex Benth., London J. Bot. 1: 347 (1842). Type: Enderby Is., Dampier Archipelago, W.A., 25 Feb. 1818, A.Cunningham 158 ; lecto: K, fide L.Pedley, Austrobaileya 1: 27 (1977). Note: Pedley erroneously gave the collecting locality as ‘Bay of Rest’, see A.R.Chapman & B.R.Maslin, Nuytsia 8: 256 (1992), for discussion.

Acacia bivenosa var. borealis Hochr., Candollea 2: 376 (1925). Type: Broome, W.A., 4 Feb. 1905, B.P.G.Hochreutiner 2828 ; holo: G.

Illustration

A.R.Chapman & B.R.Maslin, Nuytsia 8: 255, fig. 2 & 258, fig. 3 (1992).

Representative collections

W.A.: c. 10.5 km S of Yardie Ck HS towards Ningaloo, B.R.Maslin 4752 (BRI, CANB, K, PERTH); Dorre Is., A.S.Weston 10525 (PERTH). N.T.: gorge near Mt Liebig, G.Chippendale 3541 (BRI, DNA); 64.4 km W of Alexandria Stn, R.A.Perry 1565 (BRI, DNA, PERTH). Qld: c. 40 km N of Jundah, K.P.Nicolson 301 (BRI).

(ARC & BRM)

WATTLE Acacias of Australia CD-ROM graphic

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.

Page last updated: Tuesday 11 September 2018