Acacia brachybotrya Benth.
WATTLE
Acacias of Australia
Common Name
Grey Mulga, Grey Wattle
Family
Fabaceae
Distribution
Widely distributed in semi-arid areas of south eastern Australia from the Murray R., S.A., E to near Bendigo, Vic. and N to Nymagee, N.S.W. The Qld record of A. brachybotrya by L.Pedley, Contr. Queensland Herb. 4: 6 (1969), is A. victoriae.
Description
Dense, round, spreading shrub 1–3 m high. Branchlets sparsely to densely puberulous to short-pilose or sometimes velutinous with ±straight and patent hairs, sometimes glabrous. New shoots glabrous or white- to cream-hairy. Phyllodes variable, normally slightly asymmetrically oblong-elliptic to oblong-obovate (but frequently narrowly so) or obovate to oblanceolate, (0.8–) 1–3 cm long and (4–) 5–12 (–15) mm wide with l:w = 1.5–3.5, obtuse to subacute, grey-green to glaucous, with indumentum similar to branchlets, sometimes glabrous, 1-nerved per face; lateral nerves not prominent. Inflorescences 1–4-headed racemes; raceme axes 0.5–2 (–3) mm long, hairy, sometimes glabrous; peduncles 5–12 (–20) mm long, slender, hairy, sometimes glabrous; heads globular, 28–36-flowered, golden. Flowers 5-merous; sepals variably united. Pods linear, submoniliform, to 9 cm long, 5–8 (–11) mm wide, firmly chartaceous to coriaceous, dark brown or black, lightly pruinose, glabrous or hairy. Seeds longitudinal, 4–5.5 mm long, subshiny, brown to black, punctate about centre, arillate.
Habitat
Occurs on a variety of soils, often in mallee communities.
Specimens
S.A.: c. 15 km N of Overland Corner, D.J.E.Whibley 3677 (AD, MO n.v., MSC n.v., MTJB n.v.); Scorpion Springs Cons. Park, vicinity of the springs, D.E.Symon 8771 (AD, CANB, NSW, BRI). N.S.W.: E of Bungooney, Lake Cargelligo, P.L.Milthorpe 5240 & G.M.Cunningham (NSW, PERTH); 17 km S of Kaleentha Loop, J.Pickard 2578 (NSW). Vic.: 4 km NW of Gunbower P.O., A.C.Beauglehole 83508 (MEL); 25.2 km E of Nhill on Western Hwy, N.Hall H80/107 (MEL, NSW).
Notes
Acacia brachybotrya together with A. argyrophylla, A. dictyocarpa and A. spilleriana constitute the ‘A. brachybotrya group’.
The concept of A. brachybotyra in B.R.Maslin, Fl. Australia 11A: 357 (2001), is substantially revised here. In that account A. dictyocarpa was treated as the second variant under A. brachybotyra but it is now regarded as a distinct species, most readily distinguished from the more widespread A. brachybotrya by its appressed branchlet hairs and its new shoots sometimes golden-hairy. Possible intermediates between the two species occur in areas where their geographic ranges of overlap, e.g. 19 km S of Mannum on the rd to Murray Bridge, B.R.Maslin 5986 (AD, K, PERTH). The third variant noted under A. brachybotrya by B.R.Maslin, loc. cit., is now treated as Acacia sp. Wirrabara (B.R.Maslin 5999) under A. spilleriana.
Acacia brachybotyra is occasionally confused with A. decora (which has much longer racemes and appressed-puberulous peduncles).
Acacia × grayana is a hybrid between A. brachybotrya and A. euthycarpa, fide G.J.Leach & T.Whiffin, Bot. J. Linn. Soc. 76: 53–59 (1978); in that publication the latter parent was treated as A. calamifolia.
FOA Reference
Data derived from Flora of Australia Volumes 11A (2001), 11B (2001) and 12 (1998), products of ABRS, ©Commonwealth of Australia
Author
B.R.Maslin
Revised by B.R.Maslin
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