Acacias of Australia

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Acacia bivenosa DC. x Acacia sclerosperma F.Muell. subsp. sclerosperma




Occurs mostly in the Pilbara region of north-western W.A. in the Dampier–Karratha area, near Millstream and E of Newman; also the Barlee Ra. c. 150 km W of Paraburdoo. Plants from Airlie and Thevenard islands off Onslow that A.R.Chapman & B.R.Maslin, Nuytsia 8: 258 (1992) referred to an elongate phyllode variant of A. bivenosa are also likely to this hybrid. See B.R.Maslin et al., Wattles of the Pilbara CD-ROM (2010), for further discussion.


Spreading shrub 1–3 m high and 2–4 m across. Branchlets glabrous, rarely hirtellous. Phyllodes narrowly oblong oblanceolate to narrowly oblong elliptic, narrowed at base, (4–) 5–9 cm long, 4–10 (–15) mm wide, coriaceous to ±fleshy, very finely longitudinally wrinkled when dry, normally glabrous, pale green to subglaucous; midrib ±prominent, sometimes (on broadest phyllodes) with a less prominent nerve parallel to midrib; gland 6–15 mm above pulvinus, a smaller gland often present near or at base of apical mucro. Inflorescences racemose, racemes 3–30 mm long and often growing (with single peduncles arising within axil of young phyllodes); peduncles 10–22 mm long, glabrous; heads 15–25-flowered, golden. Flowers 5-merous; calyx truncate to sinuate-toothed. Pods submoniliform, readily breaking into 1-seeded segments at the constrictions, 7–11 mm wide, woody, glabrous. Seeds not seen.


Flowers June–Aug.


W.A.: 1 mile [1.6 km] S of Roebourne towards Cooya Pooya, B.R.Maslin 2738 (K, PERTH); c. 50 km due ESE of Newman, Cubana Well on tributary of Jimblebar Ck, B.R.Maslin 8832 (PERTH); Karratha back beach, 300 m E of boat ramp, B.R.Maslin 8890 (PERTH).


The hybrid status of this entity is based on field observations and morphology of specimens examined; in a number of populations it occurs (at a low frequency) with both presumed parents. Phyllodes may resemble those of A. ampliceps × bivenosa (these hybrids grow close to one another in some areas, e.g. around Karratha) which is recognized by its golden (not lemon yellow) heads, wider pods and having its lowermost phyllode gland removed from the pulvinus. Acacia bivenosa × sclerosperma subsp. sclerosperma is sometimes sympatric with A. ampliceps × sclerosperma subsp. sclerosperma (e.g. around Karratha and Millstream) which is distinguished by its lemon yellow heads and generally narrower and longer phyllodes. See B.R.Maslin et al., loc. cit., for further discussion.

FOA Reference

Flora of Australia Project