Acacias of Australia

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Acacia ampliceps Maslin x Acacia bivenosa DC.




Scattered in W.A. from the Pilbara region N to the Dampier Pen. (N of Broome) and Fitzroy Crossing in the southern Kimberley region.


Large, bushy, spreading, glabrous shrub 2–4 (–5) m high. Phyllodes spreading to ±erect, narrowly oblong-elliptic to oblanceolate, mostly ±straight, (5–) 6–12 cm long, 10–25 (–30) mm wide, dull green or subglaucous; midrib prominent, commonly less pronounced nerve parallel on adaxial side of midrib; gland 0–4 mm above pulvinus, a smaller gland often present at base of mucro. Inflorescences simple and/or racemose, racemes 1.5–4 (–10) cm long and often growing out; peduncles (9–) 15–32 mm long; heads lemon yellow, 20–35-flowered. Flowers 5-merous; calyx truncate to sinuate-toothed. Pods submoniliform, breaking readily into 1-seeded segments at the constrictions, 4–8 cm long, 5–7 mm wide, woody to coriaceous to crustaceous, yellowish brown. Seeds longitudinal, oblong, c. 5 mm long, dark brown; funicle/aril folded beneath the seed, orange-brown and waxy-looking when dry (?red when fresh).


Flowers July–Aug.


Grows along drainage lines or diffuse watercourses in sand or clay soils and appears to tolerate high levels of salinity.


W.A.: Buckleys Bore, J.B.Martin 112 (PERTH); c. 3 km due E of Wickham, B.R.Maslin 8815 (PERTH); Ragged Hills Lead Mine, c. 130 km SE of Shay Gap, K.R.Newbey 10462 (MEL, PERTH).


Possibly has some horticultural potential, see B.R.Maslin et al., Wattles of the Pilbara CD-ROM (2010), for discussion. The phyllodes of this putative hybrid are not as severely attacked by leaf-eating insects as are those of A. ampliceps.

The hybrid status of this entity is based on field observations and morphology of specimens examined; it is often found in populations (commonly at a low frequency) with both presumed parents. Acacia ampliceps × bivenosa differs from both presumed parents in having lemon yellow heads; it is further distinguished from A. ampliceps in having shorter, straighter and often imperfectly 2-nerved phyllodes and from A. bivenosa by its longer phyllodes. In the Pilbara A. ampliceps also putatively hybridizes with A. sclerosperma subsp. sclerosperma (see A. ampliceps × sclerosperma); these hybrids are less common than A. ampliceps × bivenosa and are recognized by their narrower, consistently 1-nerved phyllodes and wider pods. Phyllodes of A. ampliceps × bivenosa may sometimes resemble those of A. bivenosa × sclerosperma subsp. sclerosperma.

FOA Reference

Flora of Australia Project